Or they should at least make the people running the bots put a little more effort into it. They don't even change their spam messages! It would be super easy to automatically catch and ban them. Yes, the smarter ones will just reprogram their bot to change the message a little every time, but at least it increases the cost of doing business just a little, and will stop the stupider ones. The problem with the current solution is that it costs SE more than it costs the spammers, and there's still spam. Some of it still gets through, and enough people do business with them to make it profitable.

So here's an even better idea: just invisibly mute them, rather than ban them, so that they don't know they've been caught, and won't adapt. They can just sit there spamming their messages to nobody. And, since they won't have the motive to make new characters, it would be easier to track their behavior. Watch them buy and sell, see who they trade with, etc.