If you ever wondered how often someone is penalized for fraudulent behaviour,
forkmonitor keeps track of all penalty transactions ever broadcast. Apparently, there have been 419 unsuccessful cheat attempts with a total of ~5.13 BTC at stake since the end of 2017.
I don't think all these transactions are necessarily "cheat attempts". For example, I have read about instances in which an LN node failed, the user restored from a backup that did not have the correct channel state, which resulted in the backup-restored node trying to close the channel via an old channel state.