Even with bots, there is still a person behind them. Someone has to run it, even if a bot is doing all of the work. It would be up to that person to deal with the spammers in their campaigns.
Believe me; as much as I'd like to believe that, YoBit is absolutely terrible at that and no matter how much to complain to them, they won't budge. I think hilariousandco sent them a PM and they ignored it.
You can't be punished for errors of others on bitcointalk so spammmy campaigns are here to stay. Only participants can be banned not campaign itself.
All you need to do is ban some members and announce that publicly. The rest of participants will get scared.