What does it mean?We once double-dated, in Ed Banky's car, and Stradlater was in the back, with his date, and I was in the front with mine. What a technique that guy had. What he'd do was, he'd start snowing his date in this very quiet, sincere voice--like as if he wasn't only a very handsome guy but a nice, sincere guy, too.
I'm guessing it means seducing someone with words, but I'm looking for explanation which is more precise.
He was doing a 'snow job' : A snow job is an attempt to persuade or deceive someone, especially when flattery is used.
In your example, this Stradlater was attempting to convince this girl she had found a real gem, a soft, sincere, and genuine guy. Coupled with his good looks, he hopes to have her as putty in his hot pawing hands.
I hope her father had warned her of such Lotharios.