" And as far as a musician sitting down and writing in a specific genre?? Dude, that happens every day. You play what you listen to ( again, relative) and absorb into your mind. I can tell what a musician likes (and listens to) by the music he/she plays. If you like it, it's going to rub off on you like axle grease."
Did you understand that I said thinks about the genre BEFORE you sit down to write a song.
I would imaging that would depend on who you are or how you go about composing something I suppose. I generally begin a lot of my songs with lyrics and have only a cadence in mind when I write a song. Then I think about a melody, and I am not even yet thinking genre. I begin using different tempos to see if it should be fast or slow, and then I will decide on a drum beat. Then I will come up with a bunch of variables in my lead work. And when it comes to the instrumental portion I like to go all over the place either in syncopation or over the top or behind the beat. When I perform an instrumental never do I think about playing it in any particular genre. I just play something and see how it turns out. After I have what I want I will work out the rest. Not once do I think "Genre" in the process. I don't play everything in one genre. A lot of times I begin in one direction and end up in another. My songs generally morph all over the place and even when they are finished they really aren't. I keep changing them.
When I have to post something, they never have a classification to exactly fit what I THINK I'm playing. I play all kinds of crap and I write all kinds of crap. When I do something that turns out particularly crappy, they don't even have a genre called "Crappy" where I could post it where the people who like crappy music can find it.
But I don't listen to music on the radio or MP3. I hear it on the TV during programs, but that is pretty much changes all the time in no particular genre. I haven't sat down and listened to a CD for years. Perhaps that is why I don't do what the guy who listens to a lot of music might do.
I can't even post music on my Bandmix page or hear it from anyone else's page. I can't listen at SoundCloud or any of the other sites. Only SoundClick has a player that will let me play a song, and it is a pain at that. Most sites won't even let me in. None of the "social" sites will let me in. But that's a good thing for both of us.

I want a site that has a section called "Just listen to it and see if you like it". No professed genre's allowed. It's just friggin music. Either you'll like it or you won't like it. If you don't like it, I just wasted several minutes of your life that you'll never get back sucka. If you do like it I just snatched up several minutes of your life that you will never get back sucka. It's music.