If you rage and switch sides just because you're losing, then how the hell do you learn anything by fighting a better team- or more importantly, I wouldn't want to play with you if all you care about is winning. =/
Eh, snipers can be more useful than you'd expect. Normally I never (NEVER) play him, but last time I did some pushing with huntsman and jarate and somehow I was #1. No I did not have a low score nor did we lose.
Actually, two spies working together can be devastating. It is, however, quite difficult and you won't find two spies working together on a public server, except for mass-sapping (which is really more the case on Intel maps). 3+ spies is just silly, though.
Incorrect, one spy may take out the critical players and if he's great, he'll also sap when you attack. However, more spies means less people that attack and more paranoid enemies leads to less successful spies. You have much more need of medics.
The missing five percent is the actual chances of your team winning without following this guide (for example, Eight Fucking Scouts, with one Pyro... It's just sad... and Makes me want to join RED, and leave those BLU Idiots behind)
I disagree with whoever said 2 spies isn't a hindrance. One spy is all you need so long as he's not playing like a friggin' tard (a blind charger just trying to facestab the first person he sees, or dropping all pretenses of finesse and disguises by shooting away as soon as a RED player comes in range), and actually trying to go for critical targets - like sentries, and teleports, and medics. MAYBE even the occasional sniper. Two spies just heightens RED anti-spy paranoia and makes the job that much harder to do. Plus, the more spies, the better the chance one of them plays badly as outlined above.
However as with all the figures on the chart, player competence is the deciding factor in how true it holds.
I agree with the rest of your assessments. But as scout, I've quite literally *singlehandedly* moved the cart through three checkpoints by running in, ducking down behind the cart to protect me from the turrets, and moving it ten feet before red figured out what was wrong and killed me. Then going back and moving it five feet. Then three, then five, then seven, then another ten... I die 30 times, but I get it to the next checkpoint. I've almost won payload maps many times that way... but one runs out of time.
And when I say, singlehandedly, I mean that often... I'm the *only person* to even *touch* the cart.
Which is really the only thing to do when you're on a blue team with three engineers, two snipers, three spies, a demoman, a heavy, and a medic, who all sit back and shoot at red but never try to reach the cart.
I've done that exact same tactic of "run to the cart and hide behind it from sentries while pushing it" while Pyro, and I have to say, if the Red team is relying too much on their sentries, you can actually cap the point without them realizing what happened.