Actually quake2 at this point has very little cheaters now. The people who still play it do it because the love the game and well, we have played it for so long.
I finally stopped playing about 6 months ago. The game still has new players coming in and most if not all cry foul. They cannot believe people's accuracy and cry bot. Bots are easy to spot though and during the last year of my play, the ones who did cheat would only wall, but they would get caught eventually.
Why use a bot when everyone who has played it for 7 years has a 75% rail ratio?