Improbability dose not equal to lie.
Here is the logical fallacy behind the accusations against Ping Fu:
A causes B. B. So A.
This is absurd because, according to this logic: catching cold causes headache. I have a headache. Therefore I must have caught cold.
This is wrong, because my headache could be caused by other things, like migraine.
Yet Fu's accusers have committed the same mistake. Take the following example (it's from an Amazon review ): "The author was among a group of kids posing happily under the banner "platoon of red guards". That means Ping was one of the red guards herself during the culture revolution."
See the error in it? Just because you took a photo with some Red Guards and their banner, you are a Red Guard.
Almost all accusations against Fu have this fatal logic flaw, e.g.: "Liars remember dates wrongly. You remembered a date wrongly. You are a liar." In fact, people could have remembered dates wrongly for a number of reasons, e.g. memory mistakes. To say they are liars is logically unsound. People listed many such "evidences" on Amazon etc., claiming Fu's book is a complete lie, yet they invariably contain the above fallacy, and would be rejected by any judge in an actual court of law.
We all know people are innocent until proven guilty. Since there is no conclusive evidence showing Fu made up her story, she is innocent. Calling a innocent person "liar" is a form of libel, which is both morally and legally wrong and should be stopped.