It depends too, on what you're talking about. If I had a Roman Catholic ask me about The Calendar Issue™ I'd begin to explain maybe, but I'd be curious as to why that is their first question. If I had them start espousing an opinion on it, or get even passionate about it, I'd respond exactly (perhaps/hopefully with more tact) as you said; "What does this have to do with you, a Roman Catholic?" The same if I felt they were prying to deeply into problems of ethnicism, liberalism in certain renowned parishes, actions of bishops, problems in the OCA, etc. It would be, in my mind, exactly as if some stranger began to tell me their opinion on the inner conflicts of my immediate family. "Why is this your business?" "Why have you come to me just to rant about something that doesn't concern you?"
I might respond similarly (but with a completely different attitude) if I was asked questions about my faith from someone who wasn't interested in it, or was only interested in it as a way to argue me into their religion (which is something I've gotten from Roman Catholics often: "Tell me what you believe so I can tell you why you're wrong and why the pope is the answer to all your problems.") Sometimes, depending on my attitude, I might just not be interested in getting into it, especially if I know the person is firmly and happily in their own religion and am genuinely confused as to why they're asking me about mine. Those cases are rare because I am the type who asks just out of curiosity and am willing to extend the same to others, but sometimes I know the person, and I know they don't care, and aren't interested, so why are they asking this?
You might not (probably aren't) any of the above, and there are a million other reasons why someone might brush you off (think it's only for Greeks/Russians/Serbs/Bulgarians/etc., have never met a convert and don't know anybody who would be interested, don't know the answer so they answer badly rather than not at all, the list goes on and on. Really, I think whether you're going to get too much or too little depends more on the individual you're talking to, their perception of what's going on, their attitude in life and that day, and everything else than whether or not they're just Orthodox.