I don't know about high-level billiards, but low level billiards is basically synonymous with hustling and cheating (aka sharking.) Pool sharking is so widespread and infamous, I think it casts the entire sport in a sleazy light.

With baseball, a lot of high level players have gotten caught or admitted it, and have said that it's widespread. Jose Canseco admitted to cheating and claimed as much as 80% of players use steroids. He specifically accused Alex Rodriquez, which was later proven true. Allegations like these from admitted/caught cheats might be attempts to justify themselves, but personally I think cheating is and has been rampant in baseball for a very long time. It's still fun to watch though.