Honestly with GM tools it would be almost brainlessly easy to identify many of the worst offenders. A simple online time report, then start going and observe the longest online times for about 5-10 minutes and you could quickly tell if they are a bot.

That would probably axe a large percentage of them quickly enough. Market ones you could probably just go and look at online vs what zone they've been in the whole time. I've yet to know a REAL person who would sit in one zone for all of their online time. To nuke gathering bots, just head over to Duskbloom spawn and/or Ephemeral node for Levin mint. Watch the bots SWARM. Pick a few to follow and check online times...within like 2 hours you could scythe through the bot population and destroy many of these long standing gil farmers.