I think, in general, we should the gauge of what is reasonable to expect, and what is unreasonable.
I, personally, have never had an issue with fish, but I have with coral. One vendor who is well know around here (I will refrain from saying who it is) has pretty much broke communication with me over one chalice and one zoanthid frag. I've spent probably $3,000 with them the last 6 months, but I did buy one chalice that withered within days and one frag of red hornets he fragged the day before but said he'd "stand by" if it died. I am pretty much sick of the run around at this point.
A quote I like to stand by that I heard from Bill Gates personally is that "The customer is not always right, but good customers are always right." I believe that the vendor of the shop should discern whether you as a customer are fair, honest, and a good hobbyist who spends good money. If you are, and you suffer losses, they should replace it.
I know their aim is to make money, and Im totally cool with that. In the end I try to both get nice fish/coral AND make them money.