I'll agree, the AR' biggest concern from my experience in terms of fouling comes when dirt and debris gets into the trigger mechnism, that's when the jamming and issues become a real problem.
For me, I clean my rifle after every shoot, it has a theraputic affect on me and really helps me unwind. There is just something about the process that is just relaxing for me.
For me, I typically just wet a que-tip with some hoppes #9 and drive it into the gas key and let it sit a little while I work my magic on the bolt and locking lugs. this usually takes about 10 minutes, after letting the solvent work on the carbon build up I'll run a few more que-tips through the gas key until they come out clean.
It doesn't take much, and if you keep up on the cleaning it never gets too fouled that it makes it a total PITA to do maintenance on.
I'm a firm believer that if you take care of your firearm, it'll take care of you
Hopefully this helps.