[Argon]

Ok first let me say, there are entire websites and forums on how to cheat for every computer game including MOHAA. Now its tough to tell if someone is cheating or actually really good. I agree with you it sounds like they could of used a "no wall hack" or "no fog hack", or they could be really skilled. Couple of things you can do:

Make sure there server is running in the sv_pure mode
You can request screenshots by the team to be sent to your ladder admin.(Only problem with this is that if they know how to use them correctly they can turn them on or off, before the screenshot).
You can use the "dumpuser" command to see what skins people are using.

I agree its good to be aware of whats out there, but using them in a ladder match is completely sh%tty. I am pretty sure that I have been a victim of a few different clans that have used "hacks and cheats" during a match. Unfortunatley it's hard to prove and skilled player seem like they are cheating but they aren't.