Don't get me wrong i'm not saying that there is a right or wrong way to display an image.
But i think that the average person is exposed to so many edited images (usualy for advertising purposes) that a lot of people are looking for a beautiful yet "true" image.
I think that education as to what/why you have done to an image is the best way to encourage people to consider new ways/ideas.
There are always people who will make a decision before they have all the information avaliable to them. I question if it is worth bothering with them tho?
If you are showing your images because you like them, then others dismissing them for whatever reason shouldn't matter.
However if you are showing them to sell, then as i said above people are sold so much idealised bull...# nowadays, that lots are looking for something that is more "true". And therefore "Is it photoshopped?" is a valid question in there purchasing decision.

As a few others have already said to try and cultivate a discussion with a stranger, i find that if you are able to ask a question back and show interest in their answer you will usualy get a good response.