Here is the way I've been using these two buttons. Any facts and/or traits which, in my opinion, conflict with each other, pairings which cause me to much dissonance, I cancel out. Cross out both of them. Because I'm not intent on utilizing the entire generated description. I'm interested in coming up with a rather complete personality profile for the new NPC which somehow has become required to the scene.
Sometimes when I hit these generators I'm only looking for, or needing, one description to use. NPCs fleeting in nature seldom require much more. The other way I will use these buttons is to try and use as many of the descriptors as I can. This exercise I employ when the NPC needed deserves more nuanced, complex character profiles.