Question: I seem to see the phrase "shake his booty" being used to say something is good and attractive. But does it mean "shake his butt"? And if they are the same, why does "shake his butt" seem a somewhat distasteful action, but "shake his booty" all of a sudden becomes somewhat glamorous?

Answer: 
"Neither is glamorous! "Booty" is [American slang for buttocks](http://www.urbandictionary.com/define.php?term=booty) but almost universally refers to that of a woman. "Butt" is also slang for "buttocks" but does not imply gender. Moreover, "booty" has overt sexual overtones (and is, in fact, slang for having sex in some cases), whereas "butt" is not. (A parent might refer to his/her child's butt, but never the child's booty.) You may be hearing the term "booty" in pop music lyrics or even some forms of pop journalism, but it is not considered a professional, polite, or glamorous word. 

As far as I know, the origin of the term is int he term for a pirate's treasure, called his "booty". The metaphoric link is to a woman's "treasure", I think.
"Booty" is a word for a person's rear end from the [African American Vernacular English](http://en.wikipedia.org/wiki/African_American_Vernacular_English) dialect. I believe it probably first entered wider usage through disco music, particularly in the phrase ["Shake your booty"](http://en.wikipedia.org/wiki/%28Shake,_Shake,_Shake%29_Shake_Your_Booty). 

While it is a fairly normal word in AAVE, when used outside of AAVE it is typically used in a dance or other semi-sexualized context. So in interpreting this word, you have to pay close attention to what dialect is being used.