Frank,
not sure about distrust, from my observations,
ebay can be quite a bore with vendors offering single stamps,
the big trick is to offer complete pages.
If you have an
ebay power seller, with an established palmares, and a broad philatelic client base
then you are ahead of the game already, providing the commission structure is reasonable.
As I see it the stamps do not have to change hands, you just supply the (good) hi def scans of the stamps
to the power seller, and perhaps supporting text.
It all seems smooth to me, but always keep in mind, the world is full of trickery. Be on your guard.
I know personally, I save / budget and buy collections, part collections, pages, spending around $100 a shot, when I can afford.
One ends with good quality stamps, with good set runs, and (generally) good vendors.
Cheers