I have my own business, and in the past had a fair amount of free time to be detail oriented with the AAL. For the last 5 months or so, I've been absolutely swamped, so I haven't kept up as much as I did in the past.
In general, the vector tracing is very good quality. The typography and font work often leave something to be desired. Everyone seems to think that Arial was used in the 70s and 80s. (Arial is one of the worst excuses for a font ever made... a pale Helvetica immitator) Often the fonts are completely wrong on the small stuff... the instructions, etc. I sometimes let it slide. I often download it with a copy of an orginal scan and file it away to be adjusted later (though I've had less time to do the corrections lately).
If a file is completely effed, I delete it. I delete about 1-2 files per week that are uploaded with prejudice. Usually it's poor trace, or someone uploads one of the low res files from the MAME bezel files, or tries to pass of some other low res or upresed file. I get a lot of duplicates. I also get a lot of stuff that I think is a complete waste of bandwidth... but I clench my teeth and just try to leave it. I moderate the site quite a bit. I trim, delete, update and remove several times a week. More if necessary. I delete comments that are off topic or pointless, etc. I want the bandwidth to get used to its best potential.
I demand a high level of quality or I delete. I've had a few people get irritated at me for deleting their files, mostly because I don't contact them before I do it, or give any explanation. I don't do that to be a jerk, I just don't have the time to follow up with joe contributor and explain what the AAL is all about. If somebody doesn't "get it" and they upload garbage, I don't feel the need to educate them. Often I see that a file is very good with some minor problem. I fix those. If somebody's file was totally awesome, but one part is completely off, I usually drop everything, fix it, update it. There are a few people that contribute for self aggrandizement... they get irritated if I change a file, or if someone else uploads a better version and I delete their other version. I don't have patience for that. The best quality wins, and anybody that's doing this to see their name in "lights" needs to get a real hobby.
All of that being said, I'm normally a really laid back guy. I try to be nice to everyone, and I DO try to be courteous to contributors, and I TRY to let people know when and why I deleted their stuff. I DON'T thank everybody that contributes. I wish I had the time. I'm appreciative, though, and I know there are hundreds of other people that appreciate their hard work. There's some really cool stuff up there, and it grows bit by bit all of the time.