If you DO find that game then by all means feel free to test the waters. You may still find a casino or two out there that pays 4 to 1 on the Flush (or 6 to 1 on a Straight), but don't count on it. With that said, like Roulette this is a slow game with lots of 'push' or 'tie' decisions, so even though the edge is fairly substantial - you don't lose money all that fast. Once the bean counters got hold of the game, though, they reduced the payout on the Flush to 3 to 1, which effectively raised the house's edge to 7.28%.
When Three Card Poker was first introduced back in the 90's the odds were fairly decent - the house edge was something like 2.3%.
Games like Three Card Poker and Let it Ride are essentially 'carnival' games that have found their way into the casinos.
