Peter Lawford is an interesting example. In Pyramid's early years, he was a decent player, and was regarded as one of the best Password players as well. However, in 1979 he was washed up. Who knows why he was allowed to appear one week in '79 when he was either drunk, stoned, or both. In the one episode being traded around, Peter at first appears normal, but when he first speaks, his speech is noticeably slurred. During the gameplay, he gets hyper and can barely stay in his seat. He also got testy and frustrated when the player couldn't get the words on the first clues. Despite his inebriated state, he wasn't actually that bad of a player, although he didn't make it in the winner's circle.
I got an email from a contestant that was on that week, and she said the producers argued about whether to let him continue. One of the biggest issues, oddly enough was whether to allow him to appear without socks.