I have thought and wanted this as well. Some people record and post an mp3 of their sound here, but it's scattered among other posts so it wouldn't help me to quickly find the exact patch I want.
One technique I use is to search for a particular genre of tone on customtone. I.E. searching for "clean" brings up a nice list to pick from. A problem I ran into there was when searching for a good classic rock rythym tone, searched for "crunch" and got a whole plethora of tones. Some were just uploaded by POD kiddies who find an amp model, then crank every knob up to 10, save, name and upload it.
Another technique I used was the Ratings feature. 1st I select product HD500, then Expand View if it isn't already, then click on Rating. That brings all the 5 star rated tones to the top of the list. Currently there are 34 pages of them. I can download them all one by one into a folder on my computer, then open each one in Gearbox to test it. I know, it isn't "sampling" a patch, but it's the closest I've come to sampling "good" patches. My question here is who rated them a "5", and how many quality players rated them?
In summary, I'm with you. If customtone would allow us to upload a 300k sample of our tone (or require it ) it would greatly speed up the search for the utlimate patch!