Voter maternalism/paternalism

Today is the primary for the mayoral race in Philadelphia, which I do not vote in since I do not live in Philadelphia. However, I have been following the race closely for several reasons; not the least of which is the fact that Philadelphia politics is the ultimate reality show. I am intrigued by numerous comments that I have heard made by voters explaining why they plan to vote for who they plan to vote for, because the comments seem quite maternalistic/paternalistic. The comments go like this: "I'm not voting for Evans because he'll do more good in the State House." Or "I'm not voting for Fattah because he'll do more good in Congress." Other commenters---black commenters mind you---say they'll vote for Brady of Knox because they are white and will bring the cache of whiteness to Philadelphia.

All of these comments seem weird to me because they are endorsements in the negative. That is, they are decisions about who to vote for that have nothing at all to do with how well the candidate will do in the job of mayor. Additionally, they seem resoundingly judgmental. Is this informed voting? Is it a good idea for voters to base their decision on factors that run counter to the candidates own choice to run? Should we vote based on issues pertinent to the job at hand, or should other factors enter our voting decision?