How faculty might assess a PhD applicant who already has a PhD degree?
Here are the concerns I would have:


Is this person seriously going to spend another N-years getting a second doctoral degree, and then go seek a postdoctoral position before pursuing the job they presumably want to have? If so, what is this going to do to their career, and do I want to be party to that?
How did this person get all the way through a PhD in something other than their "ultimate interest"? Do they know what their "ultimate interest" is now?
Did they try to switch fields mid-PhD, or get some credentializing in the field they wanted to be in. If so, how much? If not, why not?
Do I think this person has strong prospects in this field? They've failed to get a postdoc - was this the result of just a small number of applications, or genuinely a problem. Again, if their postdoc application was weak, do I think it could be salvaged?