An underappreciated fact about poker is how easy it is to get cheated.
Even professional poker players can get cheated out of a lot of money in a private game.[1]
It's even easier to cheat amateurs.
There are all sorts of methods cheats can employ, from having accomplices[2] to using marked decks[3] or other cheating paraphernalia about which most amateur players are absolutely clueless.
Cheating online is even easier... if you're the one running the poker servers. Online poker is like online voting. It's not who votes that counts, it's who counts the votes.