What an exhaustive discussion!
I just returned a couple of days ago and most people in my party were affected, me the worst. Buggy things seem to love me!
Sun tan lotion seemed to keep them away on some occasions, but not on all. Don't know about the vaseline. Discouraging to hear that skins and wet suits may not offer any protection.
I do know (from personal experience) that I was affected more in covered areas than uncovered. I saw the use of all remedies--Windex, vinegar, Benedryl cream and pills, cortisone. Didn't try the Windex but the rest of the suggestions are valid--they all help to some degree, as does Witch Hazel, which pulls the poison out of mosquito and bee stings, and apparently, pica pica.
I got the worst of it my last day there--May 5. I am hoping to be bump free by the weekend and the worst discomfort was that evening--getting better day by day.
It really is hit or miss out there---you can't see the stuff. Our snorkel guide was getting stung to death on our first trip out to Hol Chan and we got nothing.