Qualifiers used to filter the pool of calls one would get for a green slip that was yours. Now we must filter for calls we will get telling us we're in the group of pilots who just might get a green slip. Oddly enough, I've even been contacted for a single green slip, in a bucket of roughly 10 pilots, for which I and several others listed were shown as not eligible.

Some GS are worth the headfake, others are not.

Qualifiers are also handy when creating auto-acknowledge slips when flying or in sims.