I personally haven't had a lot of trouble with bots, but I hear a lot of people do.
I've just checked on a couple, and whereas they were up to level 4 last week, I just found one with level 6 and 7 cards.
Thanks to johndoer123 I could find out that about 20 bots were owned by the same guy. Meanwhile, he has about 25. I told Matt about it, but although he said he didn't know that it was all one guy and they had nothing to do with it (yeah, right - they worked together before), he also didn't sound like he was going to take action. "The bots are needed to make sure everyone can play any time of day"