Well Cav, aimbots are mostly easy to pick out. For one as you said, the erratic movements, 180's and so forth. Another way you can tell is that everywhere he is shooting it is killing someone, and look at the message box in the lower left hand side (where the kills are) and if I am correct I think all of his kills will be headshots. And lastly, mostly all of them also use some kind of LMG, possibly with deep impact to get through walls and other heavy materials. I'm sure if any of the other guys knows more they will let you know, this is what I know so far
P.S. Aimbotting is also an instant ban, no questions asked period!