I'm sure that at least 40% or more of the pvp community knows about cheats and cheat clients. Some decide not to use them, but many cheat in Minecraft servers to gain an advantage. This uncontrolled spread of cheats has become an epidemic in this game - I can't even play on any of my favorite PvP servers anymore without knowing that someone is obviously hacking. Hell, every few minutes I see in the server chat "man this dude was hacking". The problem has come too far and if it doesn't get fixed soon, I'm sure people will start to quit. (It's already a major issue)
The use of cheating clients in this game is so commonplace now... it seems the best option is to not play at all.