I'm a pretty hard-core player, and tend to view some excesses the game system allows some characters to do as "cheating". Most of them are due to bugs, though; a few are due to weaknesses / imbalances in the game system, but unless they allow for ridiculous amounts of advantage, I am usually not too concerned with them. I will applaud when the weaknesses are fixed (probably with a little bit of glee), but as long as they don't impact me, my friends, or the world significantly, I can overlook them.

However, for the ones which are blatantly cheating, like hacked clients, afk macroing, broken quest abuse, etc, I am fairly vehement about reporting/shunning said folks. Many people believe that they are unaffected by what someone else does in a PvE game, but it simply isn't true. Those who exploit often ruin the play experience for others due to hogging of resources, killstealing, and ruining the in-game economy, flooding it with the ir ill-gotten gains, or inflating prices because of the excessive amount of coin they generate. Personally, I have a problem with even the excessive levelling that comes as a result as well, but that's my own pet peeve; I don't expect anyone to share it. There were a few guilds back in the day who cheated excessively (water-walking, anyone?); some of them got ganked for it (more like wrist-slap, really), the rest just went about it business as usual until the exploits were fixed, then they went on to the next exploit. I shunned those guilds and warned people away from joining them.

Some people say "don't become a rules nazi" or "you're not a dev", but I don't have to be. The rules are there for a reason. People can choose to ignore them at their own peril, but I have no issues operating within the rules and doing everything I can to protect and enrich the playing experience for myself and my friends. I'd like to think I am also doing a public service, but so often the general consensus is "live and let live" even when everyone is getting screwed over as a result, so I don't have much illusion that I am doing it for the "greater good".

Cheating is not a playstyle.