I don't know if it would be an effective "anti-Witnessing" tactic, per se, however you could really have some fun with it.
We all know that one of the big... I mean, HUGE, sources of anxiety for people wanting to leave the JWs, without raising a lot of fuss from their local Elders™ or Friends™, is the big red flag that gets raised when someone stops going Door-to-Door™. All of a sudden your Friends™ start avoiding you, considering you Bad Association™, and you get treated like crap by some of the "superfine" JWs. This "undercover apostasy" tactic allows you to have an alliance and a secrecy pact with your spouse, and maintain appearances with JWs, while you start picking up other activities to enjoy together (which will allow you to "skip" Field Service™ and Meetings™ gradually)
The other thing is that once people realize that the doctrine is crap, and the organization is full of crap, there is a real nagging within that tells you how unethical it is to try and recruit people to a cause that you no longer believe in. Granted, a lot of people aren't interested in becoming JWs. But I'm thinking, they might stop for a few moments and listen if you came to the door and had something like this to say:
"Hi, my name is ______, and I have probably called here before with the Jehovah's Witnesses. But today I'm here with a sincere personal apology. My husband/wife, _______, and I have decided to quit the Jehovah's Witnesses, and because we are now committed to being truly good neighbours, we wanted to share with you a few suggestions that you can use in the future that will keep Jehovah's Witnesses from calling on you ever again."
You can mention the "Do Not Call" list, and ask them if you can add their name / address to it.
You can mention the uncomfortable issue of child sexual abuse scandals and how the WTS denies its existence at the same time it has a program whereby known child molesters have to be chaperoned in the door-to-door work (because even child molesters are required to participate in the door-to-door ministry), and further settled out-of-court for lots of money (the amount unpublished due to a gag order which silences the victims even further) in a child sexual abuse Class Action suit.
You can talk about how in the post Hurricane Katrina assistance drive, the WTS encouraged JWs to donate to relief efforts, yet instructed them specifically to NOT indicate that their donations were to be used for Katrina relief efforts (so they would not legally be required to use the money for that purpose), and how JW Katrina relief workers assisted only JWs, who were then strongly encouraged to donate the proceeds of any insurance payments they received back to the Watchtower Society, rather than to help them get back on their feet.
There are probably dozens and dozens of examples of how the WTS is not a source of comfort for people seeking spiritual enlightenment, but rather one that focuses on sucking the life out of people and spitting out the remains when it is done with you.
The point is to give the Householders™ some valid ammunition to use in the future when JWs call again. Can you imagine how humiliating it would be to be told point blank: "Your religion is a pile of $h!t. Someone who came to my door told me that themselves."