I've been in and out of SW fish since 1974 and have bought many fish from the LFS. Most owners of LFS realize that we are just being conscientious buyers and not trying to be a pain in the posterior. The ones that don't have pretty well been weeded out, or will be very soon.
In all that time, I think I only had one person get offended when I asked to see the specimen fed. I don't remember, but I certainly think I didn't buy from them again.
I have had several times when the fish I was interested in did not eat. I would usually offer to pay for it and have them hold it for a period of time and go through the process again. Several times I would go back to find the fish did not survive, and a few times it would still not eat.
I for one am glad to be able to purchase livestock online with a guarantee. I feel that we not only get more selection than in years past, I think the quality of the livestock is much better now.
I imagine many of you are like me and can remember some of the practices we used to have. A lot of it makes my skin crawl now just thinking about it!
Chris