[pshreck]

The only logical theory is that sites 'juice' the preflop hands and flops to encourage more betting and therefore more rake. They could do this in SNG's too, to ensure it ends quicker than it should (they would make more money per hour).

While just about all intelligent online players think this is highly unlikely, I think this would be where you should start with doing some tests.

Check how often multiple players are getting high PP (JJ and up) at the same time preflop, vs how often it should happen mathematically. Think in this manner and you could do some good testing.... however I think it will be a waste of your time and you will just confirm the random number generators are working fine.