I addressed this in the "Any point playing online?" thread.
I work for a regulated jurisdiction in Canada
that offers internet gaming. We're one of only 2 regulated jurisdictions in North America that offer gambling on the internet.
The regulations we go through are excrutiating and in most cases they are the same regs followed by any site hosted in Gibralter such as Party Poker
When determining if we meet regs (and if we're trying to make a case where we don't feel we should have to) I've spot checked some various sites and found they all comply with the regs they say that they do.
Now there's no way to know if they're juicing pots but with all the hand histories available publically, it would have been caught by now if they were.
I really think it's ridiculous to believe that the major sites (PP, PS, FT, Bodog etc.) are crooked in any way. They make far too much money without juicing pots to jeopardize.
Seems to me that it's the losing players that complain the most.