Here is a stores point of view.
I find no big requests on my desk daily, but I try to bring in a few hard to find things all the time.  
http://www.canreef.com/vbulletin/sho...threadid=90850
I think most of the time it is just someone that is new, or someone that is trying to save a buck or 2.
Brian,  I have a beatiful purple tang in the store right now, over 3 months in our system.  
I agree it is safer buying from a reefer than a LFS sometimes, as mortality rate can be tough on some species.  I have a pair of Blue Throuts for sale in our tanks for months, with no takers.  A pair like this is hard to come by at the best of times.
I just giggle when I see people asking for CUC
Just my thoughts,
Ken