No. A blacklist is a cleanup, not a control. Measured on a telehealth account, 516 account-level exclusions enforced 100% — and the inventory rotated wholesale inside 24 hours, with spend going up rather than down.

On this page

• What does the measured data actually show?
• Why can't a placement blacklist fix junk Demand Gen traffic?
• How should I build a placement exclusion list?
• What actually fixes junk Demand Gen placements?
• What should I realistically expect from a placement blacklist?

What does the measured data actually show?

516 account-level negative placements were pushed on August 10, 2026. Re-pulled one day later:

The exclusions worked perfectly. 99 fresh roots served the next day, 97 of which had not appeared in the account three days earlier.

The tell that it is rotation rather than a fixed set: 52 of those 99 roots took exactly one click.

Why can't a placement blacklist fix junk Demand Gen traffic?

On Display inventory the bidder is the placement selector. With no usable conversion signal it finds fresh made-for-advertising inventory at the same rate you exclude the old.

And most of the waste is already unrepeatable: 599 of 678 excluded hostnames had one click or fewer. You are blocking domains that already took your money once and were never going to take it again.

How should I build a placement exclusion list?

Exclude the registrable root, not the hostname. These networks rotate subdomains faster than any list can enumerate — on one pull, 685 hostnames collapsed to 529 roots, with a single root serving 39 distinct hostnames, another 17, another 14. Hostname-level lists are stale within a day.

Hold shared-hosting roots out of the rollup — blogspot.com, wordpress.com, wixsite.com and similar — or you blanket-block legitimate inventory.

Know the blast radius. There is no campaign-level placement exclusion for Demand Gen. Account level is the only lever and it applies across Search, Shopping, Display, Video, Demand Gen and Performance Max, plus Search Partners. On that account, 516 exclusions landed on all 17 enabled campaigns. Say so before pushing.

Caps: 20,000 per upload, 65,000 per account. Roughly 12 hours to take effect. App placements are a different criterion type entirely, so a domain-shaped validator will correctly reject them.

What actually fixes junk Demand Gen placements?

1. Fix the bid signal. On that account the only biddable conversion goal was Purchase, while the action that actually fired — Complete Registration, 2,165 times in 30 days account-wide — was invisible to the campaign. Bidding on a goal that has never fired is indefensible on its own terms.

2. Add an audience layer. That campaign had none. A Demand Gen campaign on Display with no audience and no conversion signal filling with made-for-advertising inventory is the predicted output, not bad luck.

3. Check the channel controls. Google has been folding standalone Display into Demand Gen, so a campaign can be buying the open web without anyone having chosen that. The switches live at ad group level, not campaign. Note that unset booleans return blank, not false — control-test against a second account before concluding blank means off.

4. Check the content label gaps while you are in there. Below-the-fold and the mature/fighting game categories are commonly left un-excluded and are directly relevant to a Display buy.

What should I realistically expect from a placement blacklist?

Push batches to stop already-paid-for domains recurring. Never as the fix. A batch buys you about one day.

Related questions

My Demand Gen campaign's views exploded and sales collapsed, and I didn't change anything — what happened?

Check the channel controls before you look at creative, audience or bidding. Google has been folding standalone Display into Demand Gen, so a campaign can start buying open-web inventory without anyone having chosen that. Read the full answer.

Are Demand Gen conversions real, or is Google taking credit for people who saw the ad and never clicked?

Both, and the honest answer is that the truth sits between the two numbers. Demand Gen is structurally a view-through channel, so a clicks-only model gives it zero credit and a view-inclusive model flatters it — and the gap between them is very large. Read the full answer.

How do I stop Performance Max from spending my budget on YouTube?

You cannot switch YouTube off inside a Performance Max campaign. What you can do is see exactly how much it is costing you, fix the signal that is sending it there, and decide whether to split the campaign. Read the full answer.

Written by Usama Khan, who runs Google Ads for e-commerce brands and home-services companies at AdventurAds. Figures are from accounts under active management and are anonymised. Last reviewed 2026-08-26.