Oh, hell, if you want stories of crazy ethnic-minority Democrat politicians, just go to the Free Press website and read some shit about the Detroit city council.
As if Detroit didn't have enough problems.
Thing is, if you're perceived as representing an aggrieved minority (ethnic or otherwise), your other qualities may not matter much, and elections often go to the people who are most focused on winning them. Political office is about how good you are at getting elected, after all, not how good you are at serving the office. Crazy people are often quite focused, and so we get a lot of crazy politicians, all over the spectrum.
This is the same reason you can't buy a good toaster in this country.