There are a lot of big dudes at my gym. But I noticed something about them. Only ONE of them squats, and he squats 1/2 reps on the Smith machine. I've never seen any of them deadlift. One guy was doing tricep extensions lying on the bench with some 130 lbs on a dumbbell, and his reps involved letting it drop so fast it would BOUNCE off the floor, and his partner would lift the rest for him (he did about 20 of these). I've seen the same two guys doing bent over rows, about 10 sets, each set progressively worse and more weight. They would grab the bar in the rack, use momentum from pushing off the ground to lift it about 4 inches away from their chest, and let it fall as if no one was holding it. Then they'd repet this 3 times, re-rack, add more weight, and do it all over again.
I've seen a truly HUGE fucking guy go from doing chin-ups to doing the lat pulldown machine, pulling it down MAYBE past his forehead, and letting it go back up without any resistance.
The point is, how do these guys get so big? They train horribly!