I believe people are alluding to there being a portion of code in the algorithm that gives an edge or favoritism of sorts to risky players who bluff a lot, build big pots regardless of the cards they hold, and play nearly every hand with any two cards no matter what lies on the table. This would definitely increase rake on a cash game!
If you honestly feel a particular site is "rigged" I suggest cashing out and moving to a different site.