I thought I would follow up
Does it hurt? Yes, if you do it wrong. If you do it right its unfricking believable. *In a good way.
Is is "gay" I pondered this myself. Do "I" have any interest in male on male sex?

The answer is nope. Does having my GF "do me" this way simulate gay sex?

I suppose it depends. From what little I know about Gay sex its mostly oral. Right? So, maybe the real question is should I worry about THAT? And the answer is that if getting oral sex (or giving it to my GF is gay? Then its tough that others think this. Who cares?
If you tried it in some way that was safe for the male ego and it didn't require you to be "Dominated" (Which btw has less then nothing to do with it for us) and whoever was doing you was doing it right you would probably admit its pretty unreal.
Does it include "poop"? Well... as I said in the first post if you are not baking a loaf (sorry TMI) its pretty clean back there. Use condoms, if you really want to be cleaned out you can do that as well.