I appologize for the following rant, but I just accumulated 20% experience debt and must be allowed to let off some steam.
I was in a party yesterday where one of the members inexplicably decided to run off while members were afk and aggro everything in the region. By the time he was done, he had brought back a train so large, I couldn't even count them all. We all died. His excuse was that he just wanted to solo some stuff while he waited.
In another party (again while people were afk), someone decides to sprint through some mobs to get to an NPC to finish his quest without telling anyone. He, of course, gets aggroed and then dies spreading his exp debt to everyone in the party.
There are basically two things that I want to say about these events:
1. When you are in a party, please behave like you are in a party the whole time. Don't go off and do your own thing. If you want to do your own thing, then leave the party. Even if you're the only one who dies, everyone gets saddled with the exp debt.
2. If you do happen to get mass aggro, don't bring the chain back to the party (especially when they're mostly afk). Lead them as far away from the party as possible to minimize your and everyone elses exp debt.