Just added a new feature to YAC Exchange spreadsheet that you could find useful: a new column on the Sell list that checks if the selling user is on the scammer list (https://docs.google.com/spreadsheet/ccc?key=0AqP7ysgWb2ZHdDV2aXBXNURBZnpmYjhhN0ZmMDBGOWc#gid=9). If he isn't an "OK" check appears. If he's a "Scammer" label is added.

As you can see currently there aren't any seller on the scammer list.