Yes – cheating does occur in Texas Holdem despite the efforts of large online poker operators in trying to detect all cheaters and ban them immediately. When two or more players work together and share hands during gameplay to gain an edge, it’s called collusion. Collusion can be usually detected as most of the players who collude are not that good at poker.
The best way to protect yourself from cheating is to always stay alert at the tables you play at and take notes of suspicious betting patterns. An example of this would be when a group of players making small re-raises in multiway pots and play in a way that seldom ends in a showdown.