Nah, no bot uses an 'aimbot'.
You have to keep in mind that a bot's aiming is not really comparable to a human player's aiming... A human's efficienty in shooting is affected by: his experience, the way he handles his weapon, the weapon recoil, how long he has been steadying it, the reflexes he has, his own fear of the enemy, the "punch" he gets when he catches a bullet, how long it takes for him to steady his aim again, the surprise involved, his self-confidence...
A bot is just a mech. You can drop half these criterias
A bot just teaches you how to get better, and to pwn like a mech