It's an interesting phenomenon that every bad player on Shadow Moses almost exclusively uses pyro.
Aside from "Dedicated Sniper Regardless Of Team Size, Make-Up, Need or Outstanding Skill", bad Pyro is blindingly obvious.
Bad Scouts are generally only revealed if you make a point of out-dueling them several times and Scout is otherwise built on hit-and-run, good or bad aim.
Bad Soldiers, Demos and Heavies hide in plain sight. They're usually rather effect, if unrefined and easy to trick. I notice the occasional dalliance as a Spy because it really shows when they don't watch their backs. Even our cadre of great snipers doesn't immediately reveal a bad user of supreme ordinance because there is not much you can do to dodge a
great sniper.
No matter how "bad" a medic is, never ridicule them. I face-palm whenever somebody does: unless you're joined at the hip, you can't presume on their priorities and fears! I usually play with the assumption that I'm lucky enough he topped me off. If I get ubered or he holds my banana, the stars are alligning.
Bad Engineers are kinda two-sided. They're even more blindingly obvious than bad pyros, but they don't really need to be good for their gun to function. I still make fun of them because Engineer is the refugee of the lazy or tired player so often and a great engineer has situational awareness that would make direct combat classes blush. Putting the gun down is the first step in crossing the desert, and I've noticed that a lot of Shadow Moses doesn't even do that with perfect form.
Bad Spies.... still get lucky. Perfect vigilance is draining to keep up. And Spy is often an all-or-nothing class, or a nail-biting sacrifice class. If you blew something up(especially a teleporter these days) or back-stabbed a guy, at least you'll ALWAYS break even.
But.. Pyros? They blunder into sentry nests that you can hear through walls, they think they can out-run a good Demo's stickies or that speed-lines will protect them from the mini-gun, or FOR FUCK'S SAKE, they figure lighting the guy on fire gives them some sort of karmic edge in the afterlife.
It gets worse when they have habitually run into their death against a "helpless" 125 HP class because they think that extra 50 HP and 7% speed will defeat my ability to aim a shotgun at a growing, straight-line target.
But hey, this is just how I notice through base observation how somebody might need to tighten their form. If you think you're bad, keep playing, you'll get better. I think I only learned how to not Rocket Jump like a clown last fuckin' week.