I wish this society was of the sort where you'd be able to tell em that you appreciate them going from door to door preaching what they like/believe but aren't really interested in joining em. And then not be worried about yourself.
tableegh might be necessary for all muslims but it doesn't really have to be an explicit invitation to somebody on their doorstep. You can subtly do tableegh to your friends.
Personally, I too find their "tape recorder" style off putting. I mean, I do(used to. Got a little distracted with other stuff in life and gradually got sick of superficial and flawed logic that religious folks imply most of the time, slight offense intended towards the ideas, not the people) read, study about religion on my own but I find that Religious gatherings aren't something I would be able to sit through and not open my mind to start a debate. That's the problem with it, you can't debate with religious folks. You can't even agree with them in your own words because even the slightest view of yours that might go against mainstream Islamic/cultural beliefs might piss them off and turn all of those in attendance against you.