It's hard to know. If I were cheating on a competitive server, I'd be using cheats that gave me an edge without making me dominant. That sort of thing is very difficult to detect.

But because you were cheating you'd be above your level. So there would be a mismatch somewhere. You'd need to vastly improve your aim to compensate for bad game sense or use wall hacks to compensate for bad map awareness. Either way its not to hard for people to notice if they watch a replay. Not many cheaters are doing tiny adjustments because that would suggest they're already at that skill level.