Biggest sites are very fair indeed, like primedice, although there are people said PD is unfair, but the proof shows PD is fair.
Usually, after losing a lot of money gamblers think that they got cheated by these sites and it is common in the gambling industry. As long as I know, primedice is a game is fair enough to believe them, and they are the best in a dice game. You can also find few other good sites to play dice in this forum.