Well, they work, but they don't grip the head of the screw very tight. Is that normal? I have to apply quite a bit of pressure when removing them for it to grab.
I've got Lukie ones as well and they've served me well for the large number of games (probably near 100) that I've opened with it already. As someone mentioned though, sometimes I need to take it slow and apply a bit of extra pressure to get it started, but once a bit looser they open up without any issues.
I have a set of the cheap ones and I've never had a problem with them. I guess some of you are just getting different bits from lower quality stocks.