Probably since ugly people need more work done to their face.

I don't give two shits if they're fat, I don't want my ride to be uncomfortable because he gets two and a half seats for the price of one.

Yes, it's their fault for being fat. Well, usually.
They should not have to make skinny people suffer from their folds suffocating them :-/

@dtewi its very simple if their fat spills into ur seat just say this very politely

Excuse me sir or madam but your disgusting fat spills are touching my one person sized body so if you dont mind may you scoot ur fat ass over.

hahahahaha!!!!!

Except it's not quite discrimination as it's based on actual factors that effect the operation and delivery of service.

I just spent 26 hours flying from Busan South Korea to Toronto Canada (holly crap my internal clock is screwed) My friend had to pay 50 bucks extra because one of his bags were overweight. Why should he have to pay more just because his luggage weighs more? Because it costs the airline more in fuel and takes up more space. My flight from Detroit to Toronto was in a plane so small that an obese person would have to squeeze just to fit in two seats. The airline shouldn't have to lose hundreds, if not thousands because they have to sell one less seat (and deny someone a chance to fly) because one of the passengers is morbidly obese.

speaking of obesity and air travel. I had my first North American culture shock in the Detroit airport. We got off the plane and the entire airport staff was fat. Everyobdy was huge. After 15 months in Korea, these people looked like... not people. They were all round. It was kind of scary.

Fee fi fo fum?

Yes, that might be true. But where are you going to draw the line? And even better how are you going to enforce this? Are you going to have to buy a ticket get on the plane where a flight attendant tells you that you are too fat and that you need to buy another seat? Or are they going to have seats in the airport itself where you sit down and they check your weight right there in front of everybody? 

And what about the people that have real medical conditions? 

Well if they are being forced to buy 2 seats are they going to be allowed to sit in both?

There are lots of places to draw the line and many different feasible plans, such as specific seats for larger individuals, or, as some in the airline industry has suggested, charging people over a certain weight for two tickets, but refunding that money(all or partial) if the flight doesn't sell out.

And like any other medical condition that effects the providing of service(and isn't immediiately visible) , you can provide a doctor's note.

yea, so all people on board would be comfortable, ...like one guy said u wouldn't want to be on the plane far too long feeling uncomfortable 'coz of someone huge sitting besides you.