had issues with a Chinese DON collusion team and limited one player to a DON from that Country.
Cheating will always be a issue as long as their is the potential for some players to make more in one game than they would in a month.
Some things I often look for is trap plays and timing tells
Trap is when they are in early position and limp or call the blind with their buddy in late position either min raising or shoving,depending on desired outcome.
Sometimes people will get caught calling as the players keep min bumping the preflop pot.
Timing is when they continually are playing in a set time but in a certain position keep using more time to possibly collude.