Nobody else seems to have this problem
Actually, I suspect the problem lies closer to home. I install LOTS of extensions in dreamweaver - and none of the other vendors I install them from have had the issues with the cache. This is the only vendor where I've had to ( repeatedly) go in and dig thru my file system to delete the cache - which leads me to believe that there is a standard operating procedure being missed here.
I love Web Assist extensions - but I am learning to hate going through the install process, because of the almost guaranteed installation issues. Instead of blaming it on Adobe, somebody should be researching how other people are procedurally working around these issues successfully.