We have, theymos even posted a thread about it once. A couple people got all gung ho about it, but it didn't go anywhere. Turns out people don't want to spend their free time doing that. Go figure  .
https://bitcointalk.org/index.php?topic=90953.0

Most of us would be more than happy to have nothing at all to do with scammer tags. It's essentially a free service provided by the forum to try to help and pretty much the only thing gotten in return is complaining, trolling, accusations (no matter which way the decision goes), drama, etc. Someone gets the tag, well clearly it's because he ripped off staff. Someone doesn't get the tag, well clearly it's because staff is in on it. I do try and weigh in on high profile stuff, but that's about it. Too much hassle and grief to do anything more.