I have found that many of those low quality planets have some really nice upgrade squares. I ignored them in my first games and picked them up by influence later. Now I'm more apt to settle those near good planets in hopes of picking up a few 300% or 700% manufacturing squares. If there aren't any nice goodies on them, I still put a starport & at least one factory, entertainment spot and then mostly factories for the rest. These planets are good constructor factories. I prefer to colonize them myself as the AI seems to randomly assign labs to manufacturing squares and vice versa.
