It's generally pretty easy to sift through real spells with the fake spells. Magick is what nature can do, meaning things that occur naturally. For example, spells that "Grow wings". How many people do you know who have wings? Even if it did work, wings to support human weight would be much too large to hide with a T-shirt. You mostly can tell by what they say they can do. As much as we all wish we could cast spells like in Buffy and Harry Potter, it just isn't possible.