Was it just too obvious ?
I think it's only part of it. In my experience, the turn-off isn't what they preach and teach; it's precisely the fact that people aren't willing to do the house-to-house thing. I've heard a lot of people stating that they find that religion interesting, but they aren't willing to put up with all the requirements to remain in good standing.
So in my opinion, it's a combination of yes, not liking what they teach, but also not liking what they are expected to do if they join.