The sad thing is, I can see where, in a moment of alcohol-induced judgment impairment, compounded by being married to the annoying Maria S., that skanky maid might look hot. I would hate myself right afterward, but it would be a hot 90 seconds.
Yes, I would last all of 90 seconds by skipping foreplay and bending her over so as not to look into her face.
I've said too much.

Yes, far too much.
This shit has been pretty finely sieved already but in the interest of beating the horse on his way to the glue factory, I'll put it out there. I doubt it had much to do with finding her momentarily (and inexplicably) attractive. He just hated his wife's guts, possibly his whole family, and screwing the maid for years on end right under Maria's nose was a great Fuck You to her in his mind. Doubleugly was just a way to get back at Maria for whatever he was bitter about. In a kind of twisted way, it's a bigger insult to Maria than if he had an attractive woman on the side. "I'd rather fuck this hideous mexican than you."
Because there is NO WAY he looked at her one day and popped a woody.