Worst dorms at UC Davis?
Segundo's Regan Hall are smaller and more run down compared to the rest of Segundo Dorms. The older Tercero dorms of Kearney and Laben are also not as nice an older. If location is important to you than the three dorms in Cuarto of Yosemite, Shasta, and Tahoe would not be right for you.
Depends on your preferences - in terms of location, anywhere in Cuarto will be significantly more inconvenient just due to how far it is from main campus. In terms of buildings themselves, the older ones are generally feel more run-down, i.e. Potter hall in Tercero has noticeably dim lights and old bathrooms.