I just read Harish's http://www.sk-gaming.com/blog/5861/ and I thought I'd make a complete answer.
The fact that 'online' league and players are scorned is not new and even if the disdained people have reasons to be onliners (too young, body handicap, living in a remote area, or always busy at weekends...) there is always a suspicion of cheat.
This is the case for most games - I believe that a poorly designed game like Half-Life (not bad! just lacking modern design practices) will never be cheat-free.
Nowadays everyone is silent-running online, and more and more people can do it without hte mouse wheel. What to do? No anticheat can beat it, like no anticheat could prevent people from bunnyhopping, fastscoping and many other features.
Not bugs, features. If you consider everything you can do without tampering with the game files (and using default GUI to bind mouse wheel to +duck can hardly be called tampering) as features, then you can relax, try to do it you too, and be the one who discovers the next possibility in this game.
A few years ago I tried everything I could find to boost my game performance - from cvar tweaking and aliasing to monitor color profiles, and there undoubtedly a lot can be done! But I stopped for two reasons : I play at lans too (yes yes) and I find I'm having less fun when having an unfair advantage.
My policy is to never comply about supposed wallhacks/16bits/cvars and only stop the match (or practice game) in case of undisputable evidence of cheating (rapidfire, speedhack...). Yes, keep cool, shut it, and focus on your own performance instead of what the opponents can do.
Hey, is not that just what mature people do?