I have a policy:
If I get spam email, I refuse to do business with the company behind it.
If I get a sales phone call, I refuse to do business with the company behind it.
If I get a flyer on my car, I refuse to do business with the company behind it.
So a person with my personality would have more harm done than good by this scheme. You would be violating my space, and I don't appreciate it.
Plus you feed the JW paranoia into thinking Satan really has targetted them. Of course, like the fellow who walks up to women in a bar and says, "Wanna have sex?", he may get slapped 999 times and agreed to once, and he may use that one successful time to tell everyone, "It works!" So too, I'm sure you can find anecdotal evidence of successful results from slipping flyers on car windshields.
But you are going to piss off a lot of other people in the process, and with good reason.