Op, depends on the issue. Don't forget, most non-reporting stinkies have no MM's. You sometimes see JEFF or NITE representing the sell side, but it's actually just making quotes for larger brokerages. (Almost always Ameritrade and Etrade)
Most of these stinkies start when someone, usually an insider, simply deposits shares with a broker...places a sell order, and that order is matched with a buyer. No MM needed. OP's money gets wired from your account to the sellers account (minus the trade fee).
Brokers know exactly who is buying, selling, where they filled their orders from. Otherwise, OPtrade could flood Ameritrade with a billion bogus shares and force them into financial hell. Great way to sabotage their competition.