Look people, art in any form is just an expression of some feeling or idea. If you don't relate to it, don't look at it, listen to it, etc. No one is gluing headphones to your ears and making you listen to rap or country or classical music.
For those who don't get the foul language in rap, just think about how corny it would be to have a girl in bed talking dirty to you and she called it a "penis." "Oh baby, please insert your penis into my vagina repeatedly with a great deal of force." --Lame right? Or how about watching the Sopranos and someone kills someone and says, "Why, I declare, sir. I do believe that his life has now expired." -- Out of character and stupid, right? It is sort of the same thing. For those of us who like rap, it is not that we lack a vocabulary or necessarily grew up in the inner city. I grew up on a farm in Kentucky, and I like to think that I have a larger than average vocabulary. When I listen to some rap, yes "dirty words" and all, I sometimes dismiss the lyrics because I enjoy the beat to dance/move to or the lyrics get me sort of psyched up. It is sort of the same feeling you get from listening to some heavy metal. Different songs bring out different emotional responses in different people. That is the beauty of diversity.
Lighten up, some of the songs are just party songs. They are not meant to be put in Palgroves Anthology of Poetry! If you don't like them, there are so many other artists out there competing for air time and your dollar, that I don't think you will be forced to listen to music you don't like any time soon.
Try to have an open mind. I find that I enjoy most every genre in the right situation. Country, rock, rap, hip-hop, jazz, blues, even bluerass and folk music, at times.