Wyden also called on the FTC to require greater transparency from ad blockers, including disclosures of whitelist payments in both the ads themselves as well as to people downloading or installing blockers. This will help people "evaluate and compare" ad blockers to see which ones live up to their billing, Wyden said.

We've asked Adblock Plus' parent, Eyeo, for comment. The FTC has confirmed receiving the letter, but hasn't said what it intends to do.

There's no guarantee the FTC will take action, but complaints about whitelisting have circulated for years. Wyden explained that companies like Amazon, Google, Microsoft and Verizon (Engadget's parent company) have long paid "millions of dollars" to bypass ad blockers, partly negating the point -- why run the tools when you're still going to see ads from companies with deep pockets? This won't force ad blocker companies to stop all sales pitches, but it could help you switch to a more effective solution.

Update 1/14 7PM ET: Eyeo told Engadget it had been clear on how Acceptable Ads worked, having "fully briefed" the FTC in 2016 and had been "100% transparent" with users. It further argued that Acceptable Ads had expanded to an "open and transparent ecosystem" with independent oversight. You can read its full statement below. That FTC briefing and transparency don't necessarily mean Eyeo is in the clear, but it's evident the company plans to stand its ground.