You'd be surprised. When I play heavy, a lot of stuff goes over my head since it's such a complex class.

A lot of people think it's just an easy class where you hold m1 over the enemy, but they don't understand that m2 allows you to spin your barrel but not fire, which can fake the enemy out. In fact one of the most exciting meta games in tf2 is watching two heavies duke it out, since a lot of times it's really not about aim but about the sheer determination and willpower and how badly each player wants it.