Some of you who have been around shells for a while may remember some years
back when a certain fellow published just such a report, spiral bound, with a
separate page for each shell dealer.  Each dealer was rated on a number of
criteria, which basically boiled down to quality of specimens and quality of
service.  Alas, dealers who didn't rate very high in various areas were most
unhappy, and expressed their dissatisfaction with responses ranging from
nasty letters to threats of lawsuits.  The publication was soon taken off the
market, never the like to be seen again.
Regards,
Paul M.