Our own claim: "It's not ACOS, it's TACoS" — does it still hold?

“The point is for the account to make money, not for the ads to make money. It's not ACOS, it's TACoS.”

This one is mine. I have said it many times, and I still mostly believe it. Which is exactly why it belongs in the ledger: a claim I like is the one I'm least likely to check.

TACoS — ad spend divided by total sales, not just ad-attributed sales — is read as the "honest" ad metric. If TACoS is falling while sales grow, ads are doing their job: building organic demand that you no longer have to pay for. If it rises, ads are carrying too much of the business.

Every conclusion below rests on these. Reject one and you can see which conclusions fall with it.

• ✅The value of advertising is in growing the account, not in the ad's own numbers looking good. I still hold this. An ad can show a poor ACOS and still be what brings in the customers who buy again without ads.
• ⚠️TACoS captures that value. Only loosely. It's a ratio with two moving parts, and either one can move it for reasons unrelated to ads working.
• ❌A falling TACoS shows ads are driving organic growth. A falling TACoS shows the ratio fell. Total sales can rise from a promotion, a season, a competitor going out of stock, or a price change. And TACoS also falls if you cut ads and the business shrinks — just more slowly than spend.
• 🔶Organic sales = total − ad-attributed, so the gap is what ads built. That gap is a residual, and a residual is an upper bound, not an estimate.

Conclusion: the principle holds; the metric is a gauge, not proof. TACoS tells you the ratio of ad spend to the business. It cannot tell you whether the ads caused the growth. For that you need methods that compare against a world without the change: holdouts, staged spend cuts read against a control product, and placebo arms that are deliberately left untouched.

The full step-by-step decomposition, including how AI joins the reports, is in the course.

Experience (one example), Hypothesis (the claim as a whole)

The cleanest example I have of TACoS pointing the wrong way is a shutdown. When I switched off all advertising on one of my smaller brands for two weeks, TACoS went, by arithmetic, to zero — the best TACoS possible. Over the same two weeks, retail revenue fell 59% and non-ad visits fell about 35%. A metric that reads "perfect" while the business loses more than half its retail revenue is a gauge, not a judge.

Verdict: ⚠️ partly. The principle holds: judge ads by what they do for the account, not by how they look on their own. The ratio does not prove it. Use TACoS to watch; use holdouts, controls, and placebo arms to decide.

Type, in detail: Hypothesis (the claim); the shutdown example is Experience.

Have data that says otherwise? Share a case. Reversals are published.