Supernatural, Season 2

Dean:
I'm just saying, man, there's some legends that you just...you file under "Bull Crap".

Sam:
And you got angels on the "Bull Crap" list?

Dean:
Yep.

Sam:
Why?

Dean:
Because I've never seen one.

Sam:
So what?

Dean:
So, I believe in what I can see.

Sam:
Dean, you and I have seen things most people couldn't even dream about.

Dean:
Exactly, with our own eyes. That's hard proof, okay? But in all this time, I have never seen anything that looks like an angel. And don't you think that if they existed, that we would have crossed paths with them, or at least know someone that crossed paths with them? No. This is a demon or a spirit. You know? they find people a few fries short of a Happy Meal and they trick them into killing these randoms.