I've caught scum once or twice looking for people who often asked questions like "What do you think of X person?" It's a way to control and redirect town activity, pointing towards targets deemed appropriate by the scumteam, distracting them from others deemed more dangerous. In general, I prefer not to ask those questions for that reason: looking for scum-teams is generally ill-advised unless you have one of them pinned, squirming, and spewing scumtells. And then, they're going to be trying desperately to distance themselves, if they've got a grain of common sense. I prefer to ask for lists of reads on all players present, in order to get the same effect with more data and with the negative effect cloaked a bit.
Asking about lurker policy of someone who isn't a lurker (i.e., almost any time outside of RVS) is usually a subtle a call for LaL or to pull away from the main argument, which is a great thing for a reasonably active scumteam.
I think the necessity of LNCP to answer such a question is debatable. In general, answering a question is necessary. However, I still consider the "what the hell is this?!" response reasonable, so long as it doesn't occur too frequently.
As far as the "you're paranoidal" being inappropriate, it's one of those side-dodges that I just don't expect anymore. Someone challenges your right to ask a particular question, you explain your intentions or at least make some effort at expressing a Plan Being Afoot.
Eh... I guess the point here is that an entire chain of "your question is bad" is possible at any one point, and I can say "okay, one dodge," but two dodges is where it starts getting dicey.