Of course white people can sing the blues. Happens all the time. (Good for you, VTam.)

As for 'aping the accent,' if you got a reasonable sample (let's say 500) of southerners from the same area with the same level of cultivation and recorded their speech, I'm sure Mudcatters could not tell the whites from the blacks.

Of course, accemts are changing as more northerners move south.