They will do all kinds of things to make you look foolish, point out minor mistakes, etc. as a indirect way make themselves look better. This goes for people in general, IMO, not just JW's.
You're right on there. Witnesses are not the only ones who practice that. Lots of people do this, and don't even realize it. (myself included).
I would have to say, though, that witnusses are some of the worst offenders; it's like "the church lady" from SNL. Asking probing questions all the time; finding things out; going on assumptions; gossip; bad assosiation.
I cannot stress enough how truly bizarre I found this behavior. It was like you were out getting grilled by elders whilst working in service, rather than being upbuilt and saving people from satan, LOL! I would get asked about all kinds of my friends, what we do in our spare time, etc. I would give them answers that would give them more questions.
Example:
So, what do you like to do in your spare time?
Oh, I do lots of things. (evasive answer)
Like what?
Oh, you know, what everybody else does I guess. (evasive answer)
So, how is XXX doing?
Oh, pretty good. (evasive answer)
I heard that he/she has not been getting to many meetings.
Humph. I hadn't heard that. There's so much gossip going around these days, it's hard to know what to believe you know. (evasive answer)
Practice the above and you will have tedious long boring conversatins with your fellow "brothers and sisters" who are interrogating you.