How can you tell someone has a modded controller in COD 4?

SOme people genuinely can fire fast like blame truth, but sometimes with the g3 and most pistols they're shooting so fast the game can't even track it. is there any definate way to tell?How can you tell someone has a modded controller in COD 4?
when you see someone shoot their handgun like an automatic weapon likewise when you see someone shoot a sniper rifle like an automatic weapon.How can you tell someone has a modded controller in COD 4?
when the gun goes crazy fast.