Is rescheduling an interview bad?

If I was conducting the the interview I can tell you right now, your fired. But if it is a normal person and they had an interview spot open the next day most hiring managers won't care, especially if you wow them in the interview. Sure there is always the one asshole like me, but look at it this way. If you can't make it to the interview, you are guaranteed to not get the job. At least rescheduling, you have a chance.

If you make it to the face to face interview, you are doing good. Based on the normal progression from telephone interview with the recruiter, then a phone interview with HR representative and maybe even a phone interview with the hiring manager first. If you have a legitimate reason, the hiring manager shouldn't care. You could say you are already committed to a meeting on that day. Sometimes those things work in your favor. If they think someone else is interviewing or interested in you they might just want to beat the other company to the punch and make an offer. Just like a car salesman "this car is pretty hot, it might not be here tomorrow, you should buy it now before it is gone". If you can't make the date, you can't make it. There will be another job around the corner. If they don't reschedule, that just might be a blessing in disguise.