I guess it depends on what counts as junk. It seems like allowing false advertising or outright malicious scams should be an ethical if not legal issue. Howev

I guess it depends on what counts as junk. It seems like allowing false advertising or outright malicious scams should be an ethical if not legal issue. However, seeing as Amazon calls them defects, it sounds more like they're just non-relevant ads. Sellers might have a case that they were paying for some level of targeting and and getting worse click through rates than advertised.