Its really easy to tell the difference between a true story and fictional one. The problem is, if you can tell the story is fake despite the fact it is labeled otherwise there is nothing you can do about it. God forbid you should challenge the authenticity of the story for the author will soon turn around and get annoyed.
My favourite 'fake true story' is when the person trapped someones feet while they were looking for something under a bed and tickled them for hours. This is really really common, although I think these days people are more inclined to post that as a satire on other 'true' stories.
Its sad people would label it true just to get more views. If they're so inclined to write a story, they should simply write a fictional one and leave it at that. The story will get views if the story is good, not if its true.