You simply flag accounts that meet certain criteria. Quests that are always skipped, do they always use 32bit client and click to move, are they inputing commands for 4 hours straight with no afk time. Many other things that could be learned by simply looking at the forums of the different bots out there. The money part is training people how to spot the bots and having them use the bots themselves and checking in on the flagged accounts. Tons of other things that you can spot easily if they cared enough to learn about the bots and watch how they behave.