The thing about any "community" that is well-defined enough to justify having its own conferences is that it has its own set of foundational assumptions and jargon, and conventions. If you don't know these things, you're going to have trouble participating at a high level.
I don't think it's so much that people will not "pay attention" to you - it's probably just that what you are saying isn't very interesting. The thing about non-theory CS people interacting with theoretical CS people is that they usually present exactly the same arguments/problems/ideas that everyone else does. Believe me, you get _really_ bored by the seventeenth time you have to address the question "but what if the theorem prover has bugs in it?!", pronounced with the swagger of someone who believes they have just hit upon a novel idea.
I imagine that if I turned up to a gathering of high-energy particle physicists, I don't think they would pay much attention to my thoughts on the subject either.
It's not dismissive behaviour, either. It's actually just a common mistake within CS to believe that you can turn your hand to any part of CS - you're essentially participating in a very high-level discussion.
To answer the original question, I've found people in the top echelons of theoretical CS to be extremely patient and friendly.
I asked some really silly questions of top researchers (in one-on-one or small group situations) as an undergraduate that probably deserved to be answered with disdain - I still cringe in retrospect. The most biting retort I ever got was "Oh, that's covered in <such-and-such-a-paper>, which is worth reading if you're interested in this". Hardly a telling-off. For the most part, people have always taken the time to explain things from first principles, or re-state them in ways that I could understand.
The idea of the ivory tower is a bit of a misconception. You're talking about very, very smart people who are usually more than accommodating when it comes to answering genuine questions or just engaging in discussions. I would jump at the chance to talk to them about anything and everything - it'll be interesting to say the least, and they are some of the nicest people you'll meet in CS.