David, I have trouble sleeping sometimes for a number of reasons I won't go into on here which explains the late night/early morning activity on forums sometimes lol.

Sounds like you may have found someone who may be able to help, just keep an eye on what they ask you to spend in order to possibly sell something. Your right in that it is subjective & people vary enormously so finding your target market can be a bit of a minefield, having someone who knows about art & how to place it should help. I know from my work designing signs & vehicle livery how difficult it can be even though what I do isn't art.
Course it's not all subjective, once you have made a name for yourself you can sell any old tat at silly money & people buy it just because of who produced it regardless of any like or dislike for it lol.