From my understanding, when you dispute an item, they take the TL out of the equation. If that particular TL gives you some history, your score may drop. If it is a newer baddie, it might boost your score until verified (if it is verified). That's why disputing just before you try for a mortgage or auto may not be such a good idea. The important thing is really to get as many baddies off to start with a fresh slate.
Does that mean you should dispute in hopes of increasing your score? NO! This could easily backfire.
Collections and public records do not apply are never exempt
Ohhh, so if I were to dispute a collection, they will just mark in dispute, but no score change should occur? That's good news.