I hope you made a point of not keeping the magazines. I dont mind entertaining them for a few minutes, but i never keep the magazines.
From what i have experienced, when most JWs are preaching, they are not used to having a real conversation, so when they find someone who is willing to discuss a few points, they are completely caught off guard and unable to converse.
The last time that happened to me, a young man, walked in my garage while i was working on my car, and hit me with a typical pre-packaged introduction for the magazines and drop them on the top of the trunk and said " well , thank you. Have a good day". I told him "wait" and i questioned him about a few things, he was so caught off guard , that he just looked at me with nothing to say..
I honestly think most witness are not really that interested in having long conversations. They want to just say a few words, drop a magazine and move along to the next house. Preaching has truly become an obligation, and as long as they can fill out a report card at the end of the month, they are happy.