Spotlight - stuck on what file(s)?

I see lots of people have/had problems with Spotlight indexing. My question is, how do I figure out which file(s) are causing the problem?

The most common non-Terminal answer is to add the entire hard drive into Privacy, restart into Safe Mode, take it out of Privacy, restart, and indexing happens and everything is better. This doesn't seem to work for me. I haven't yet tried the commands to kill the hidden Spotlight directory. I'd like to figure out which file(s) are causing the problem - for example, if it's related to iPhoto, then just put the Pictures directory into Privacy. Although I don't think it is related to iPhoto - when I log in as a different user, the same indexing-forever behavior happens.