Some of the trades that they accept make me feel like I'm cheating. For instance, I've traded the two utilities for like $1000. And they're desperate as heck to get Boardwalk and Park Place. Granted they're great properties but they'll screw themselves over to get them. Sometimes it seems a little too easy.
It also gets annoying when you're playing with a friend and whoever wins usually comes down to who can manipulate the CPUs out of their money first.