how to know a fake

Don't or do? You are supposed to tell them they are fake, that's what make a caster. They know what's real and fake.

If spells can't make you become these creatures, how come there is a section for all of these spells though?

It's the "fantasy" section. Since members are able to upload spells, and they continue to do so, a section of pure "fantasy" was created to store all that. Please note the comment on the fantasy section which says "T hese spells are all fantasy based. Most true practitioners of magic do not believe that these types of spells are real."

If it sounds fake or makes you question it, it is probably fake