Never really. Most householders are either apathetic or , if they wish to disagree , confrontational. Even those who had strong religious convictions never made any effort to convince me that their religion was right or brought up any reasonable argument that I had been fooled.
I do remember being asked by a sister to a call she had on a local theology student ( normally I would avoid these kind of discussions like the plague but no other elder would go ) & we spent an hour debating the trinity. He knew his bible a lot better than me ( like most JWs my bible knowledge was limited to a pretty sketchy knowledge of JW essential scriptures like Mt 24:45 ) and he pretty much won the argument. But even then - it was purely a theological doctrinal discussion.
Maybe this kind of "reverse witnessing" doesn't work anyway.A couple of years ago the local Mormons came to call & I invited them in. As they were in a cult not dis-similar to the JWs I tried to talk to them about obvious untruths in their religion but they just weren't interested. Not even willing to discuss anything. Anything "negative" was just dismissed as lies from apostate ex-Mormons. "We trust our Prophet." was pretty much their stock response.