From the poet...
"What is this life if, full of care,
We have no time to stand and stare."
From PaulB...
"...but surely if the person him or herself wants it then putting them out of their misery in a responsible easy way is the humane thing."
Then we have 'Body Dysmorphic Disorder.'
You will see via the link below that this is not all about 'Cosmetic' foibles. Some folk are sure they have too many legs, for instance.
Perhaps the answer is to have a committee along the lines of a firing squad. Where, in the latter, only one rifle has the live round, in the former only one opinion shall, in the end, decide?
http://en.wikipedia.org/wiki/Body_dysmorphic_disorder