For me it's the respect part. When I'm a player, I try really hard know my character and use their abilities RAW to the best I'm able. Same as if I'm a DM, I try and run the game, within reason, RAW. The understanding with my group is that with 5+ editions of rules in my head, in both instances, it's not always possible, but it's not intentional if I fudge something that's an honest mistake, I always try to be fair. When I put my time and effort into playing my character or DMing a game and someone cheats, they no longer have my respect. Not understanding or knowing the rules is one thing, outright cheating is another. If I catch someone cheating, there's no warning, no talking to other than get out, you're not welcome here anymore.