I like fish stores that have been established for a bit. They have coral that they have kept alive for some time, usually in a display tank in the shop. A new place has all new stuff unless they just moved to a different location. Anyone can order coral and keep it alive for a week (AKA *****) to sell it...the coral is stressed from so much bouncing and moving...new tanks don't sustain them right..all kinds of possible problems to consider.
For example: The healthiest sponge (an invert) I ever had came from a petshop where the sponge had been in his tank for about 6 months, it had grown behind some rock where it fell, and nobody purchased it (an orange tree sponge)...I had that sponge for over 5 years, but all the other sponges I have purchased died within a month. If the coral you want has been in the tank for a while and is all bloomed and healthy...IMO...that's the coral with the best chance to make it.