There are services with offshore brokers who routinely find shares of pink sheet stocks to short..Timothy Sykes built an entire stock service based upon this premise....my broker wont but some ahole will, though you are correct that most of this stuff happens with MM
I'll take short sellers when I'm long a stock especially when they start to tip the scale. Short sales create future buyers to close their positions. It's when everyone is long on a sure thing that I'm concerned as possibly too many future sellers without enough shorts needing to cover.