Many years ago Tom Hill (in an upholstery cleaning class) advised us (only half jokingly) to tear that label, the first moment the client was looking away.
The "S" label usually (not always) means that the manufacturer does not want the consumer to mess with it. It is about liability, not clean-ability.
The "S" must stand for "S"tay away "S"kippy.
Most of the sofas with those labels will clean just fine on the wet side with mild pre-spray, a mild rinse and good technique. I've done a few hundreds. It is always wise (unless, like Chavez, you want new furnishings in your home. I think he calls it: Marry Christmas honey) to test before hand on the zipper side with products that are somewhat stronger then what you intend to clean with, to check for bleeding, change of hand, distortion etc. And yes, it is a good idea to play it safe, considering who the client is and potential loss of business.
Dry cleaners are lousy cleaners and unhealthy for you. Dry foam is o.k. if there's absolutely no other choice. It works great particularly on totally clean fabrics.
On the other hand, for liability reasons and straight from our legal department: What do I know?
