My Charlie was named Bad Andy by his previous owner...he was "just a wittle kitty" and would get into lots of trouble!
When she gave him to me (she already had three cats), he was almost seven months old, and not as "bad" anymore, so I said, "you're not Bad Andy, you're Good Charlie".
I also think Charles is a very dignified name, and cats are very dignified animals. The nickname Charlie is just plain cute and suits him to a T. I wonder if I shouldn't have named him Sunshine, though, because that's what I call him most of the time. He just lights up my life.