A better place for this question is probably OMNI.

Here's an excellent source of information regarding all things Gambling:

http://wizardofodds.com/

The author is a professor of gaming at UNLV, an expert in mathematics and statistics. He even writes trip reports.

You can read through his "ask the wizard" section, and he has a section on online gambling, including a blacklist.

Basically, he has determined that some online casinos do cheat in their blackjack games.

One way they do this is by "dealing seconds". The way this works is that if the player stays on 16-21, the system moves on to the dealer. If the dealer's two card total is 12-16, it will check the next card on the top of the deck. If it would bust the dealer's hand, then that card is burned, and the dealer gets the second card off the top of the deck. This dramatically reduces the number of times the dealer busts, adding signficantly to the house's edge.

Some online casinos deal a fair game, and in a fair electronic game, the expected results electronically should be exactly the same as the expected results in a physical game.