I just want to say "thanks" to the OP for posting this here, so other divers will read it. I'm sure you've raised the consciousness of at least a few divers who might now rethink their buddy practices the next time they find themselves in an instabuddy situation.
I've done lots of dives with instabuddies (and I personally love that word, hyphenated or not - it's just captures the essence of the unique relationship!). Most have been great, several not so great, a couple disastrous. I thoroughly agree with Bubbletrubble's list of questions to ask an instabuddy. I learned the hard way NEVER to assume that other dives know (or remember) what's "the norm" - e.g. surfacing after 1 minute if you lose your buddy, etc. Never assume they have common sense, either. Everything should be discussed upfront - and if the instabuddy seems to feel you are doing overkill in the pre-dive discussion, then end the relationship, because that's not somebody you want to buddy with. I've had that happen - if my new buddy displays the slightest indication of not taking the pre-dive discussion seriously, then I'm not diving with that person.
Even with the pre-dive talk, things can still go wrong on the dive. If they do, then I will want to talk about it in detail before the next dive. If my instabuddy doesn't see a problem, or clearly state what he/she will do differently on the next dive, then I will not dive with them again.
I've been doing lots of instabuddy diving lately - I've been helping out in the galley for a local dive boat, so I've been going without my usual buddy, and finding buddies on the boat. And I'll be doing it again next weekend. So this is an issue that is very much at the forefront of my thoughts right now.
Thats pretty much what I had said earlier and I agree completely. I may notbe as tactful as some others but it is my dive as well. Are you diving out of Ventura, if so what boats are still up there, Peace, Spectre ?