I've played maybe a couple dozen games on MWS, and I've had really good luck so far. The worst I've gotten was people leaving without saying gg after they win or lose, but that's no big deal. All in all, most people have been polite enough.
I'd say don't sweat it. That guy's a jerk, but just find another game and forget it.
EDIT: Also, personally I prefer to play against tournament-worthy decks, which a lot of times means net-decks. I play a lot of net-decks myself so I can get a feel for how they work. It's a great way to learn a deck inside and out. But if someone shows up with a janky deck, that's fine, it's a good test because you face those in tournaments, too.
Check out the
Texas TCG Players forums.