I find it doesn't work, at least not all the time, the reject all. I have a couple MC/DMC's I have carefully trained on one of my farm teams that is an experiment with 4* players, but I kept getting offers for 'em and an ST as well so I wound up assigning points to make the offers stop.

Alternately, it's a fun way to sell your guys without have to list them if that's what you want.