i'd posit that if an employer can't find a decent pool of current employees to potentially pair program with an interviewee, they have deeper problems than getting that upcoming interview right, and need to correct for some past hiring mistakes ASAP.

i would definitely be looking for employment elsewhere if i my co-workers were so unpleasant that i thought they'd turn every pairing session into a pissing contest (and i say that as someone who generally prefers solo programming as far as immediate enjoyment goes, but who finds that pairing is often useful and/or necessary).

And then you know that employer has issues and to avoid them.

Idiots have a negative impact on any type of job search. I have been in interviews where I showed a valid solution for a problem but failed because it wasn't exactly the one the interviewer wanted. On the other hand if I did pair programming with somebody and it worked well this would be a strong indicator for a healthy comonay culture.

That's actually another reason why pair programming is good: The interview is just as much a signal to the candidate as it is to the employer. If the developer he's pair-programming with is a douche, it's a good sign for the candidate to run and not look back.