So, there's been threads about RPG abilities that would be good, or what D&D classes one would take IRL, but what about abilities that would be *bad* to spontaneously develop?

To make the challenge easier, this doesn't have to be bad for a fully clued-in Playground optimizer - you can even explain how it would be bad for someone with no gaming experience, or even someone from a parallel world where that particular system doesn't exist.

Is it bad because they might not understand the consequences? Bad because it's hard to control? Bad because they might come to rely on it, and find that it fails when they need it? Bad because other people *would* recognize it, and fear/persecute them?

Just how bad can we make this "gift" of abilities of an RPG character?