Aww come on. Do you seriously think what Senator Biden said was racist? Or are you just being overtly PC? What he said was funny in the vein of something Bill Cosby would say. It's something we all notice and can individualize with, which is exactly what makes it funny. He wasn't being derogatory unless you think working in a convenience store isn't honorable work.
I've gradually had to throw out about ninety percent of my joke repertoire because of all the idiots trying to "out racist" or "out something-ist" each other.
Everyone on the planet is a racist to a certain extent. What would you call someone who had a phobia requiring him to only associate with people NOT of his kind? I can tell you this much, if what ever it's called ends in 'ist' it must be bad.