A: First of all, I think most stereotypes exist because there really are people like that. My job as a writer is to make sure that I am faithful to all of the people and places I'm depicting and that I help the reader to see the person beyond the stereotype.
But here's the insidious thing: In writing minor characters, stereotypes are an easy shortcut for the writer and offer a comforting familiarity to the reader. Sweet little old lady . . . corrupt politician . . . bigoted bully of a small town sheriff . . . effeminate homosexual . . . sulky teen . . . dumb blonde . . . the list is endless. Just say that small town sheriff has a belly hanging over his gunbelt and has piggy eyes behind his mirrored sunglasses and we all have an idea of who he is. But he's basically a stereotype.
The fun thing is to play with the stereotypes by giving that character an unexpected trait. Maybe this sheriff stops to take a box turtle out of the road and put it safely in the grass at the side of the road. Maybe he hums arias from grand opera. Maybe, in the dead of night, he leaves a bag of groceries for a poor black family. Now that sheriff is no longer a stereotype.
I do try to develop even minor characters beyond stereotypes -- and the bigger a part the character plays in the book, the more I try to show various sides of their personality. Look what happened to Birdie when she had a book all to herself! There was a lot more to her than meets the eye. I suspect that the same could be true for any of my so-called minor characters.