Unless Ameriquest "changed" the appraisals, I can't see an independant appraiser risking their license and going to jail for $400 bucks. Appraising is by no means an exact science, but since the savings and loan fiasco, since 1989 they have to follow very strict USPAP guidelines.
There have been a lot of examples of "friendly appraisals" around the country. Just look at the Poconos several years ago.
http://www.poconorecord.com/report/price2high/
You may think this never happens, but it has happened before, particular in LA. History repeats itself.