Is Larry David Right? Can Dogs be "Racist"? This is a Job for Cesar Millan

While my best friend "Redford" is a happy-go-lucky, super-social, tail-wagging, progressive-minded, equal-opportunity pooch, he's deathly afraid of security guards and has taken an unexpected nip or two at the outstretched, friendly hands of homeless people. And he almost always growls at them. How does he even know they're "bums," who are generally just nice gents who want to pet him? And why doesn't he like them? It's embarrassing, and, if he were ever to bite one, dangerous.

Then, there's the common urban myth -- or truth? -- about dogs and African-Americans. Some say that dogs can't see darker faces as well, and so act nervous or hostile. In any case, search "racist dog" on YouTube, as I just did, so as to find the Curb Your Enthusiasm episode below that my friend Lindsey and I watched last night (and that sparked the posting of this question), and you'll find hundreds of videos. So something's going on here.

My question is, what?

And how do we teach our confused furry pals that security guards, homeless gentlemen or African-Americans aren't anything to be afraid of? This is a (strange) job for Cesar Millan, my idol.