In my experience with them knocking on my doors they NEVER want to say they are jw's. I once asked a woman 3 times in a row, "are you a jehovah witness?" she would not identify herself as one. On my last and final very loud time she finally admitted it.
Years later in a jw discussion with my jw I asked him why, if they are so proud to be 'one of' jw's then why won't they even admit it at the doors? His response was that if they did people would just shut the door in their face. So, you know people don't want to talk to you and yet you still insist on annoying them? and that is their 'fine witness'.