The AMUSF is just another association like NCCA, etc. The membership is mainly RE UPHOLSTERERS and RENOVATORS of furniture, with a few retailers.
Perhaps DFS regarded membership a waste of time and money, in much the same way as most c/c's look at membership of the NCCA.
DFS have a massive share of the market and many buyers will get their suites cleaned just as owners of furniture from M & S, or REIDS, etc, will.
The real rubbish comes from IKEA............