Sirena Eternal

How do i exclude demos from my searches? Sometimes I want to browse the cheep stuff but don't want to sift through 500+ pages of just demos. I tried using "-Demo" or "NOT demo" Since I heard that was a think, but the "not" in caps followed by a word doesn't actually do anything but search for items with "not" and "demo" in that order. I really would like a way to filter out demos.