I was just in the mall and saw this tall statuesque GORGEOUS redhead holding hands with a squat chubby pug-nosed girl who looked like a 13-year old boy. And I was just wondering what's the psychology of this?

Actually, you see this kind of thing pretty often, so there must be some kind of common underlying psychological thing happening here. You rarely see two beautiful lesbians together. If you see a really pretty lesbian, she almost always seems to be with an ugly girl. Why?

It seems especially strange because with heterosexuals, women are incredibly picky about looks. You would NEVER see a super-hot model-looking redhead holding hands with a squat, chubby, effeminate-looking man (unless maybe he were very rich and/or famous).

So what is the special chemistry between hot & ugly lesbians? What psychological need is fulfilled for the hot girl by being with the ugly one? I know it's not just that Girl A happens to love Girl B. There's something more to this phenomenon, I'm certain, because you see it way too often to just be a coincidence.
"Beauty is in the eye of the beholder" is not an acceptable answer. You see the hot/ugly dynamic way too often for it to just be individual choice.