What is Selling Out?

We have all heard the phrase " selling out" a band that has perhaps taken a new direction, or a person who suddenly beleives in one thing one day and another the next. It happens.

I was on MSN and was chatting away to a friend. As usual I was listening to Green Day, what can i say I'm almost famous for it. So a friend of mine deicded to debate whether or not that Green Day had infact sold out. Everything from American Idiot, backwards, is apparantly crap. So I respected his opinion on it and moved on to another topic of conversation. He was like a dog with a bone and wouldn't let it drop.

So he deicded that Green Day was just drone, " one, twenty one guns" As an example.
The music was medicore and they sold out for political beleifs and because they are deffered as mainstream to some bands.

So I explained that every band can't stay the same forever, change is good, drastic changes can be for the good as well. But he still called this selling out.

So I put it to him like this

" Personally I think selling out is hard to pin on a band. Green Day for example tried new things, new instruments and techniques which you could either love or hate. I thnk selling out is actually not doing new, creative things and sticking to the cliche of what music should and shouldn't be. Punk music as a rule used to be about uniqueness. now its about what sounds original which is two of the same things.

Defining what is and isn't selling out, is just opinons and expectations of what should and shouldn't be allowed for a band"

Sorry If I bored you all, but I'd like to hear your opinions on this.