You can imagine the kind of thing… so-called protective potions that are really gravy with a bit of bubotuber pus added, or instructions for defensive jinxes that actually make your ears fall off… Well, in the main the perpetrators are just people like Mundungus Fletcher, who’ve never done an honest day’s work in their lives and are taking advantage of how frightened everybody is, but every now and then something really nasty turns up.