I don't remember reading official rules on the subject but I think it's fairly logical to have the ability, as a GM, to give characters new negative qualities if the situation is appropriate. The most obvious example would be to get a criminal sin after being caught by Knight Errant (and possibly released after calling the right contact asking for a big favor).
But I'm looking at some other negative qualities that could be acquired due to hard circumstances. Loss of confidence and Scorched are good examples. If the character gets many tattoo and decides to get really distinctive piercings the GM could give him the Distinctive style negative quality.
I had a couple of opportunity to give qualities during play so far in my game but I'm really prudent because I'm not sure how doing so changes the game.
So my question come in two parts:
- Are there any official rules in 5th edition (4E, 20th anniversary is "good enough") on how to handle adding new negative qualities (do I have to give their value in karma to the player kind of rules) outside of addiction
- Does adding negative qualities lead inevitably to a grimmer, grittier campaign (to the point where characters are just stuck with a bunch of them they can't get rid of?). Back your answer with actual experience please.