I gg every game I play, and I never /spec out of something I'd normally lose.
If someone's flaming/trolling me or another player, and I'm present in the room, I'll /kick or /ban them, sometimes during a match, but that's only in very extreme cases where they're actually violating rules by making sexist/racist slurs and such. I think that's as close as I've come to cheating, other than messing around with dm thresh for lulz at other admins, or for events, and what not. (See: Getting enlightened by Dad)
When I see someone /spec out of a fight, or /quit during a fight, I just nod, and note them down as a subhuman piece of trash that doesn't deserve to share this planet with me. Since I can't end their life over the anonymity of the internet, I don't let what I can't control frustrate me that much.