I am reasonably sure this is not true. I have seen at least three profiles deleted following my reports about the authenticity of the profile in the last month. It is inconsistent but I am reasonably sure AW do follow up on at least some reports of fake profiles. I suspect they only delete obviously fraudulent profiles eg face pic on the profile shows a different person from the veri pic. It is very difficult to prove fraud and SP’s can cheat the system in a variety of ways, but if you have good evidence of fraud it is worth reporting it.
The OP asked "do AW check forums and act on negative reviews?", my reply to that was in my opinion no, they do not read forums and act on negative reviews on them. The fact they respond to reports made directly to them and take down fake profiles as a result of those reports is not the same thing as them actively reading forums to act on reviews.
Bear in mind AW will, and have, taken down legitimate profiles and keep any credits that have been accrued on those profiles, but I can't see them doing anything about the fact 'Betty Big Boobs' got a negative review on UKP because she had a wiffy fanny.