Playing bum notes is never fine and playing the wrong notes, which you thought were the right notes, isn't good either.
One thing I find guitarists do a lot is to play a song wrong because they were too lazy to listen to it and work out the parts. Interpreting a song is fine, if that's what you are doing, but I don't like lazy short cuts.
There are cover bands that just approximate a song, which is OK, and those who play them straight. We have a new drummer in our cover band who is very good, but annoys the hell out of me because he doesn't see why changing the rhythm of a song is a problem! I think he's just being lazy and doesn't want to learn the arrangements, or maybe it's ADD.