Last year the feed store "expert" picked two Turken pullets for me from the SR bin by dangling them from the head. She claimed the girls would hang limp and the boys would squirm. I ended up with one of each gender, so I suppose her method was 50% successful.
THIS year she picked two Silkie pullets for me by checking feather growth on their wings and tails (she claimed cockerels have slower tail feather growth and uneven wing feathers), and the outcome has yet to be determined. Even among vent-sexed chicks I manage to gravitate towards the cockerels and bring them all home.