To me fair is playing a shot with intent. If you snooker someone because the 9 is over a pocket, it's because you know there's a combo on next shot. If you see the chance for a 3-foul, play it (especially when people don't bother trying to get out of a snooker). If they mess up and leave you a chance to win, it's their punishment.
Annoying is when someone just bangs the balls around in the hope of fluking the 9. They usually lose, but it's annoying and feels unfair when it's you they get the fluke against. I never play them again.
Unfair is when someone deliberately fouls. Unfair is when someone runs after agreeing to BO3 or after a fluke. Unfair is
when someone wants you to agree to rules which they prefer rather than the ones the games is supposed to be played by
.