Barry's unique card-counting abilities were seen as such a threat by casino bosses that even when he gambled in the hotel where his own show was on he had to be flanked by a team of security guards.
"When I was there last October I was in the Palms hotel playing Blackjack at the table," he revealed. "I was making very irregular bets so the dealer started calling me Rainman, after the movie.
"Eventually she called the pit boss over, who studied my game pattern and asked me to leave the table and said to me, 'We'd rather not have your company tonight Mr Barry'.
"The next thing I know a few of the other casinos had sent out representatives to watch my show, where part of my act was to memorise a deck of cards in 20 seconds and that was that, I was banned from all the casinos."
However, the Waterford illusionist is adamant all was above board with his game-playing technique and says he never cheats at the casino tables.
According to the star: "I don't really card count when I'm playing, I like to mix it up a bit and vary my bets.
"The idea of blackjack is to reach 21 so when a lot of people reach 18 or 19 they stop there. I like to take a risk and go that extra card which I suppose they found a bit odd.
"It doesn't bother me that I'm banned, it's par for the course, really."
But despite his gambling ban Keith will return to Las Vegas this May for an extended run of his hit show.