I visit Audiogon almost daily on either an iMac or a Macbook Air, both running OSX 10.12.2 Sierra with Chrome as my usual browser. I've never seen any of the ad behavior you're describing.
I don't have Firefox installed but did test extensively this morning using Safari and still didn't have any of those issues.
I don't have Firefox installed but did test extensively this morning using Safari and still didn't have any of those issues.