First-time listener (specifically for this thread); first-time caller. I'm not a sound-engineer or Apple Genius or HID professional, so... yeah.
My experience w/APP: Just got them two days ago; one bud passed the test the first couple of tries while the other failed, and now they both fail regularly unless, it seems, I'm pressing them harder into my ears during the test. I've ordered the foam tips from CharJenn (sp?), but probably won't receive them for another week.
The over-arching problem is that the buds, or more specifically the tips, don't sit deep enough in the ear canal. No matter the material used for the tip, if it isn't inserted deep enough into the ear canal, it won't make a good seal. And as noted previously in this (loooong) thread, without a good seal, you won't get good bass response or noise-reduction/-cancelation.
I'm not sure yet what purpose the opening everyone is cleaning with tacky goo serves, but my suspicion is that what makes it help is that the users are also cleaning the surface of the buds, making them stick for a minute deeper in their ear canals. It's great that it helps, and good for y'all if you don't mind doing that regularly, but... that isn't a fix for the overall problem. Our ears will get "dirty" (for lack of a more disgusting term), and anything designed to be inserted into our ears needs to account for that truth.
I think the answer is: deeper insertion, either in the form of longer tips or some extension that can be securely inserted between the bud and the provided tips. If your ear-structure is such that you get a solid, quiet seal already, you're good to go; if you don't, then the deeper reach of these extended tips will probably resolve the problem. (It might also be true that *bigger* tips would work -- big enough that they can get a good grip inside your ears despite not being inserted deeper into the ear canals. If the foam tips I ordered don't work, perhaps I'll try to make bigger tips myself somehow, maybe by inserting something underneath the outside flap of the current large tips to expand them, or by surgically affixing the outside flap of another silicone tip over the APP large tip to add heft.)
The most important thing to me is the sound-quality of my headphones/earbuds, and it seems like the APP are really good given their limitations (small, wireless buds versus large, wired, over-the-ear headphones) -- so, I want them to be able to work as well as they can. I'm pretty confident that the solution would be longer tips/deeper insertion.
Just my $0.02.