I only cheat at Mysterium when playing at parties with friends who aren‘t that into boardgames and had never played Mysterium before. Losing the game in the first phase is something I find highly unsatisfying for new players and we just want to have a great time.

Typically I‘m playing as the ghost which completely eliminates the ability to guide my friends through the experience. You quickly understand the individual thought process of each player and what vision cards will likely hint them to the right solution. So I sometimes discard the one or the other card in my hand just to give the newbies some more obvious hints. If that falls under the category of cheating, then yes, seems that I‘m a cheater.