NewBie type questions - How does 51%er attack work?

[twolifeinexile]

What happened exactly??
51%er double spend or spend bitcoins with a zero balance account then accept in their block, since their block is faster enough that their block chain grows faster then honest block calcs (which will reject fake spend) and eventually people have to accept?
What if people realize it and even they think they will not reverse the action, since that fake coin is still being able to be traced, and since the probability of reverse is not zero, people may accept the blockchain , but they do not have to accept fake coins as a payment (you pay me with fake coin, I reject to give you back services, since there is a possibility it is reversed.)

So not sure how 51% attack work.

[DannyHamilton]

There is no need to ask the exact same question twice in two different sub-forums.

See my other answer in your other thread here:

There are a couple of 51% attacks.  Here is one possible example . . .

[twolifeinexile]

Sorry for double posting, I initially posted on newbies forum then realized this is may be a technically question that this board may have better answers.
Again, thanks for your help.