Before You Spend Another Rand on Google Ads…

Does Google Advertising Pay?
By Claire (because Paul said it depends and Steve said nothing at all)

As most of you know, we didn’t set out to build a bookshop. It happened—like most great adventures—completely by accident. And that means we had a lot of learning to do along the way. Sure, I had Paul and Steve advising, which helped tremendously. Paul, to his credit, is now in Week Two of his new 1,800-calorie-a-day diet and claims to have already lost 3kg. I remain deeply suspicious. Men lose weight like it’s a hobby. I could run a Comrades Marathon in ankle weights, and I wouldn’t lose a gram unless I gave up all carbs, hope, and the will to live.

But I digress. This business? It’s unlike anything either of them had worked on before.

Most businesses sell new products or services. They have a set number of products they stock deeply, and as they sell out, they replenish. Simple. Stable. Predictable. If you’re selling car service parts, for example, you might stock five types of 5L engine oil—5W-40, 10W-40, 15W-40, 20W-50, 0W-30 Long Life for the Volkswagens—and keep 100 of each on hand. You sell, you restock. There’s supply. There’s demand. There’s consistency.

Secondhand books? Completely different baby.

We don’t have 100 units of anything. We have 10,000 SKUs and most of them exist in a single copy. And even if we do have two copies of the same title? One might be a hardback. The other a paperback. One might be as new. The other might be in good condition, but with slight curly corners and a handwritten name on the cover page. So they get listed as entirely separate products.

Which means the way our business works is entirely different. We don’t rely on big wins. We don’t sell one thing a thousand times. We sell a thousand different things, once each.

That changes the way you look at profitability. It changes how you think about inventory. And, most importantly for this blog, it changes how you think about Google Ads.

“Let’s get to the point: Google Ads might look like they’re working—until you actually do the maths.”

The Illusion of ROI

3kg-down-Paul, of course, thinks this section should include a cost-benefit matrix and a sensitivity analysis. He even suggested colour-coding our emotional responses—green for "mild optimism," orange for "borderline panic," and red for "Steve accidentally boosted the wrong ad again." Steve, on the other hand, quietly nodded and went back to adjusting our daily bid strategy. Which, frankly, may or may not have been for socks.

Google loves to tell you your ads are generating a high “return on ad spend” (ROAS). And sure, it sounds impressive. There’s a graph. There’s colour. There’s even a percentage that makes you feel like a boss.

But ROAS isn’t profit. It’s just gross sales divided by ad spend. It’s sales, not success.

Let’s say:

• You spend R1,000 on sponsored ads

• You generate R2,000 in sales

• Your profit margin per item is 10%

Your actual profit on R2,000 in sales is just R200.
But you spent R1,000 to get it.
So you’re R800 in the red.

“That’s not advertising. That’s just very expensive donating.”

Imagine standing at a market stall handing people R50 notes every time they agree to take one of your books home. That’s basically what’s happening when you’re not tracking your margins.

And don’t even get me started on how many people accidentally include their shipping fees in those gross sales figures.

The Real Maths

When I asked Paul how much we’d need to sell to make back our ad spend, he launched into a ten-minute breakdown involving marginal tax rates and something called "economic order quantity." I zoned out halfway through and started wondering if Zoe the dog could be trained to bark every time we run an unprofitable campaign. (Spoiler: she cannot. She just thinks it’s treat time.)

Let’s say your profit per order is 20%. That’s pretty decent, especially in retail where anything above 25% is unicorn territory.

If you spend R1,000 on Google Ads, how much do you need to sell just to break even?

Let’s do the maths:

• You need to make R1,000 in profit

• At 20% profit margin, that means you need to sell R5,000 worth of books

So your actual required ROAS is not 200%. It’s 500%.

“Yes, you read that right. You need to make five times what you spend on Google Ads just to break even.”

That’s not small business-friendly math. That’s “hope your best-sellers are on steroids” math.

What No One Tells You

Steve once tried to automate our entire campaign performance reporting using a script that worked perfectly—except it also sent alerts to the team every time we made a sale under R60. Which, in a secondhand bookstore, is basically... 90% of them. My phone had a nervous breakdown.

Meanwhile, 3kg-down-Paul added an "ROI Alarm" to his spreadsheet. It plays the sound of a cash register when we break even, and a sad trombone when we don’t. You’d be amazed how often we hear the trombone.

Everyone talks about conversions and clicks. But no one talks about the silent killer: your margins.

“If you’re not tracking net profit—not just sales—you won’t even realise how much you’re actually losing beneath the surface.”

It’s like filling a bucket with a crack in the bottom. It looks full from the top, but give it five minutes and you’re ankle-deep in regrets.

Also, Google’s reporting dashboard isn’t your accountant. It’s not going to tell you that R2,000 in sales cost you R3,000 in stock, courier fees, packaging tape, and the physio appointment after Claire slipped trying to dodge Zoe mid-picklist. (And let's be honest, Claire falling over things is basically a weekly calendar event. The only mystery is what day it’ll happen.)

So, Does Google Advertising Pay?

If you’re a fellow small business or entrepreneur reading this—first of all, welcome. Secondly, let me say this: we’ve paid the school fees so you don’t have to.

We’ve run the campaigns. We’ve watched the analytics dashboards glow like a Christmas tree. We’ve crunched the numbers, cursed the margins, and tried to convince ourselves that maybe that 197-page pivot report meant something other than “you just donated five grand to Google.”

If any part of you is wondering whether you're doing it wrong or whether you're alone in the ad-money wilderness—you're not. We've been there. We've Googled “why does Google hate me?” We've tried switching agencies, audiences, headlines, and yes—even fonts.

“If you’re not calculating the true cost of customer acquisition, you’re not just wasting money—you’re inviting it to leave with a handwritten thank-you card and a complimentary tote bag.”

Google Ads can work. But only if:

• You have high enough margins

• You’ve done the maths in advance

• You’re monitoring profit, not just sales

• You’re targeting the right kind of traffic (not just window shoppers)

Even then, it needs to be tested, tweaked, and babysat harder than a toddler hopped up on a full box of chocolate Easter bunnies.

At ReadMatter, we’ve tested it. And while it works for some categories (hello, niche collectibles and first edition Stephen Kings), we’ve learned to be very careful. Because it’s not about how many people click your ad—it’s about whether, after all the wrapping and courier slips and bubble wrap and customer emails… you’re actually left with more than you started with.

And trust me, nothing ruins your love for an ad campaign faster than realising that after R1,000 in spend, three hours of packing, and fifteen emails later… you’ve made a grand total of R47.23.

So before you launch your next campaign, grab a calculator. Do the maths. Check your margins. Have a snack. Maybe cry a little. Maybe Google 'jobs that don’t involve spreadsheets, bubble wrap, and strategic existential dread.'

Either way, make sure your Google Ads aren’t just working for Google.

Because trust me, Google already has enough money. And unlike me, Google doesn’t cry in the stationery aisle at the thought of buying another pack of thermal labels. They don’t need your money unless it’s coming from actual, trackable, margin-friendly profit.

And if all else fails, hand the campaign to Steve at midnight and ask Paul for a pie chart. Just don’t ask them both at the same time—we tried that once and ended up advertising horror novels to people searching for cake recipes.

“Because here’s the truth: clicks don’t keep the lights on. Profit does.”

And somewhere in the middle of it all—between the spreadsheets and the packing slips, between Steve's scripts and Paul's sad trombone—we must acknowledge the greatest injustice of all: metabolic injustice. Yes, Paul eats two lentil bites and drops half a wardrobe size. Meanwhile, I run a bookstore, a family, and the metaphorical equivalent of a marathon every day and still can’t lose a gram unless I give up oxygen.

But hey—at least when it comes to Google Ads, we’ve learned to out-sprint the losses.

And if you're feeling a little bruised from your own ad spend experiments, just know: you're not alone. We've been there. We've got the spreadsheet scars to prove it.

In fact, we’re considering starting a support group. Something like Google Ads Survivors Anonymous. We’ll meet every Thursday, drink too much coffee, share ROI horror stories, and maybe—just maybe—finally agree on a keyword strategy that doesn’t cost more than rent.