I needed a plasterer at short notice to tidy up a wall after kitchen cabinets had been removed. I'm sure it's hit or miss, but as it happens, the man who showed up was not just a great character, he was old school, as far as knowing what we needed. Fair price too, and lots of experience.
He did a nice job -- better than we'd hoped; even did some extra we hadn't mentioned (a break on a corner of the wallboard where the hole for the door frame had been broken through into the next room).
It's certainly potluck, but we got lucky this once.