↳ marketingengineer / field note
Smart Bidding is only as smart as its inputs
Stop tweaking tROAS targets and start auditing what the algorithm eats. A field note on value rules, conversion quality and the inputs nobody checks.
A pattern I keep seeing in account audits: weeks of energy spent nudging tROAS targets up and down, zero energy spent on what the algorithm is actually eating.
Smart Bidding is a function. Garbage in, confidently-optimised garbage out.
The three inputs that matter
Conversion completeness. If 15% of conversions never reach Google Ads (see the server-side tagging teardown), the algorithm learns from a biased sample. Fix the pipe before touching any target.
Conversion value honesty. Most shops send revenue. Revenue is a lie the moment margins differ per category, return rates differ per product, or new-versus-returning matters to you. We switched one account from revenue to a margin-weighted value — same campaigns, same targets — and watched the algorithm quietly shift budget toward the products that actually make money. ROAS looked worse. Profit was up 14%.
Conversion latency. If your sales cycle is three weeks, last week’s spend has reported almost none of its conversions yet. Judging — or worse, letting an automated rule judge — on a seven-day window punishes campaigns precisely when they’re working.
The one-hour audit
- Pull backend conversions and Ads-reported conversions for the same 30 days. The gap is your data leak.
- Take your top 20 products. Multiply each conversion value by actual margin. If the ranking changes, your value signal is misleading the algorithm.
- Plot days-to-conversion. Set your evaluation window past the 90th percentile.
No scripts, no tooling, one spreadsheet. I’ve yet to run this on an account and find nothing.
Targets are a steering wheel. Inputs are the engine. Most accounts I open have someone wrestling the wheel of a car that’s running on fumes.