@stuartk
I agree 100% with you that “no-one should have to install anything -- that Audiogon should take whatever measures are necessary to prevent this stuff from showing up on the site”. Your response is the correct response.
This is why I suggested you send your email to support@audiogon.com and say the giant blue Amazon ads are appearing. please include what device you are using, what browser and the date and time. Please confirm your software is up to date. This info will enable Audiogon to determine what is wrong and to fix it.
In addition, I also agree Audiogon needs to handle this and I should not have to add an ad blocker to my iPhone. I was completing some research and the ‘blue ads’ were causing me issues. Thanks again for posting this. I hope Audiogon quickly fixes this. And, obvious, you do know.