I've heard from others what
@tankguy mentioned, that there are certain areas that they are harvested from that tend to be more resilient than others. I don't have any firsthand experience with them though.
Intesting read from 2008:
http://reefkeeping.com/issues/2008-01/eb/index.php
"Based on epizootiological, field, laboratory and aquarium studies to date, I can offer a tentative explanation of the recent history of
Catalaphyllia in the trade. Early in the history of reef aquariums,
Catalaphyllia were probably more common than they are today in patchy distributions in shallow, easy-to-collect-from areas. Over a period of approximately 10 years, these areas were probably overexploited and collectors moved to different and more marginal areas, including nearshore areas with higher pollution and lower water quality. Although pathogens affecting
Catalaphyllia are unknown and diseased specimens appear rarely in the field, some specimens affected with ECS may have been introduced into exporters' facilities. Exporters, wholesalers and often retailers tend to keep the same species in the same tanks. A highly infectious waterborne disease that affects a single species would be expected to have ample and multiple opportunities to expose and infect healthy colonies before reaching the end users."
"It is interesting that over the past year, more and more healthy appearing
Catalaphyllia specimens are being found in stores, including those recently collected in Australia."