When surgeons perform elective surgery, the mental condition of the subject is taken into account.
This is done for two reasons:
1) Make sure that the subject really does want the surgery in question
2) Make an assesment that the subject will give it a go themselves if necessary, possibly doing themselves some harm.
Now, number 1) is pretty easy. If a woman wants bigger boobs, they go through a pretty thorough grilling. I know someone who just wanted a lift, and she said the interviews with the surgeon reduced her to tears. They have to be that thorough. I would imagine it is the same with all such procedures. What man wouldn't want a bigger willy, but will it actually cause you mental anguish if it remains as is?
Number 2) is a little harder. In some cases, people have gone to the extent of amputating their own, healthy appendages, because they are that unhappy with the way they look with that appendage in place. Seriously, there are people who feel that way. Now, if you lop your leg off, there is a good chance you will bleed to death. With any such things you might die of resulting infection.
So, there have been cases where a surgeon and psycologist have agreed that someone is THAT do'lally, that they have decided it is in the best interests of the subject to amputate, lest they end up killing themselves.
Perhaps cosmetic surgeons are worried that MJ will buy a big pot of playdoh and some superglue and DIY his nose?