OK, then just humor me and try it. Take one of your capped supps (preferably small cap/fine powder), swallow most of your saliva first, then open the cap and pour it under your tongue. As your mouth starts to generate saliva, start moving your tongue around a bit, and push down on the powder, as if you're trying to force it into the tissue -- under the tongue, into the gums, roof of your mouth, wherever it ends up (but try to keep most of it under your tongue). And refuse to swallow for as long as you can. Gradually, the grit of the powder will disappear and the taste will fade. I believe this is a pretty good indication that it's absorbing into your oral tissues. Let me know what you think.
And sublingual actually is a valid delivery method -- I just feel that it's under-utilized. Interesting discussion, nonetheless.