Well, it doesn't bother me because Modding usually means something that is created that everyone agrees to play on for laughs and a good time. When one person creates a hack to ruin the playing experience for others, I have a problem with that. Usually most hackers really suck at the game and I'm able to take advantage of that despite the hacks.
Like this one hacker in cod4, a buddy and I stayed in the server to combat this guy, he had wall hacks and was able to shoot through almost everything except for floors. I remembered there was this one building with 2 entrances to a basement, but no way to pick us off without poking a head down the steps, which we were able to exploit because we'd be able to see him before he was able to poke his head under. Was able to beat a hacker, he left as soon as the round was over after calling us various names and insulting our mothers.
If some one creates a mod that alters gameplay, like a pac-man server for a shoot'em up game or something like that, that's cool as hell, or if some one decides to create a zombie mod, yeah, it's a good change of pace. I'll pop on those every now and then just to kick back and relax and be goofy.
It's like candy. Teachers always say that candy is ok if there's enough to go around the classroom. Same goes with modding, if everyone gets to join in on the goofy fun, then it's acceptable, if it's 1 person using mods to an advantage against other gamers then that's when they deserve the kick.