www officialpokerrankings com for those who don't know is a great way to see if a player your playing has unreal winning percentage. Anything over 50% roi is probably a house player or a bot. And it's FREE.

I think also that the hero stories and professionalism marketed with skills to win by the sites and also this type of rankings would be evidence of non-fair game.

There is much less psychologic factors in online poker than in real life and
even there skill factors gives only limited benefit between players of
at least basic understanding of the game.