It seems like almost everything I like fits this category. Especially when it comes to food. There are various theories as to why everything wonderful and luscious will eventually kill you. My mother, a nutritionist, claims that during human evolution sugar, fat and salt were rare. Because we need them in small doses to survive, those people that craved them and ate them survived and passed a genetic or cultural affinity on to their descendants. Then of course we progressed to the point at which we can get far more than we need, and satisfy our cravings not just occasionally but at every meal. I, on the other hand, think that there might be some inherent human need to define all that we enjoy as dangerous. In a scientific self-obsessed age, we still have temptation, but it is no longer seen as having moral consequences. Instead we have replaced that focus with a focus on consequences for appearance and health.