I heard a rumour a few years ago that SS require their cask OBB to be served with an aspirator (a device which puts a blanket of carbon dioxide into the barrel, making the ale last a day or two longer than it would without one), and in the eyes of CAMRA this disqualifies the ale from being "real", i.e. using artificial means to preserve the beer as opposed to letting it mature naturally. This might be a reason that CAMRA aren't specially keen on SS, however, I've seen various SS pubs in the Good Beer Guide, but not for a couple of years now.