Originally Posted by QuantumIguana
I've never seen anyone claim about Harry Potter "Schools of magic don't work like that!" And 50 Shades is sex fantasy, which has never had that much to do with reality.
1. When you bring magic into a story, then the way it works should be consistentand logical in itself, and NOT poor man's deus-ex-machina.
As for magic schools: there actually ARE different systems of belief why and how it works; google: hermetic magic, chaos magic, alchemy, shamanism, vicca, voodoo etc. Some knowledge about mythology, ancient religions and mythical creatures doesn't hurt either. The Potter books are a brilliant example how to fail here.
50 Shades: unlike the previous example this is one I haven't read myself but as far as I understand it it's a case of writing about BDSM whilst knowing chickenshit about it.
BDSM itself isn't fictional, thus proper research on what, how, (and from psychological POV why) should have been undertaken by the author.