I usually don't mind the computer cheating to much. The extra challenge makes it fun. I only get annoyed when it allows them to come back from nothing, or beat you at the last second (catch-up factor.)
My most annoying defeat by a computer was in Generals, Zero Hour. 3 humans, and 3 computers. We were playing a custom map that had me placed right next to a computer sharing a supply source (so we would fight it out from the start). Well first thing I do is place a turret on his side of the supply's and I succeed in stopping him from getting resources. I count the value of his buildings, and destroy his supply depot's so that he can't do anything, then proceed to build up my base to move out. About 5 minutes later, this computer is bombing me. I couldn't figure it out, he never once gathered any supplies, and somehow he gets up to bombers? I checkout the replay afterwards and discovered the computer gets free resources. Every 5 or 10 minutes I don't remember how often, the computer was just given money. That really annoyed me.
My most annoying defeat by a computer was in Generals, Zero Hour. 3 humans, and 3 computers. We were playing a custom map that had me placed right next to a computer sharing a supply source (so we would fight it out from the start). Well first thing I do is place a turret on his side of the supply's and I succeed in stopping him from getting resources. I count the value of his buildings, and destroy his supply depot's so that he can't do anything, then proceed to build up my base to move out. About 5 minutes later, this computer is bombing me. I couldn't figure it out, he never once gathered any supplies, and somehow he gets up to bombers? I checkout the replay afterwards and discovered the computer gets free resources. Every 5 or 10 minutes I don't remember how often, the computer was just given money. That really annoyed me.