Beware of superstitions
I know the actual rules on video blackjack games are horrible, but a bartender was telling my friends and I that the way the machine pays out has nothing to do with the game. Basically he said that they set up the machine so that all of the games but one will take your money, if you find the one game it will pay out a lot. I know there are a lot of holes in what he told me, but is there any truth at all to this. Do they really set up those games so that most of the time you have no chance of winning?
When it comes to gambling, there are many superstitions abound. One machine will have an abnormal positive variance and everyone will think that machine has been set to win.
It is the nature of humans to find pattens in otherwise random data. We have made constellations out of smattering of stars. Our imagination forms familiar images from puffs of clouds. Masses are drawn to water stains that seem to resemble religious figures.
In any case, I pretty sure Nevada law requires video machines using cards simulate actual decks. If this is true, two machines with the same rules have the same expected value.
One more thing, bartenders are rarely an authority on anything but making drinks.