Sounding black hurts your income; so does sounding southern
freakonomics.blogs.nytimes.com
freakonomics.blogs.nytimes.com
In my case, people often tell me that I have a very clear British accent; but when I ask them to pin down what sounds so particularly British, I often flounder about and eventually answer along the lines of "well, you speak very precisely and in a very educated manner" -- which says something about our (or at least, Canadians') stereotypes about the British!
In light of this, I wonder to what extent the judgements made about whether people "sounded black" or "sounded southern" were in fact merely that people were picking up voices which sounded uneducated -- and having subconscious racism translate that into a sense of blackness or southernness.
I think you mean "with a generic region-free American accent".
Carla: You're from England, huh.
Eric: How'd you guess?
Carla: Because you sound smart even when you say stupid things.
--CheersThat being said, a lot of black people I know change their accents depending on their environment -- work-related, vs. passing time with friends. They (we) are often cognizant of the fact that you need to speak crisp, clear English, as not to be thought stupid.