I agree with you, Little_Socrates. Scent can have dire consequences for some people.
I realize that people are defensive about ensuring that their personal boundaries extend far beyond their bodily space with their fragrance, but...it can be rude to wear fragrance in some environments.
And no, I don't think it is the responsibility of homeowners to have signs plastered on their doors warning people that someone inside that personal space may have issues with some scents. People are entitled to their privacy about such matters. It isn't the public's business. But, it is the business of people who make it their profession to go door to door to exhibit a sensitive attitude to whoever may be behind the doors they knock on.
And that is where the JWs are rude. They aren't just going to the grocery store and wandering around. They are deliberately and knowingly entering into other people's personal spaces.
It is a no brainer. Don't wear scent when you are going door to door. Simple.