I find that if you impart the information without being condescending (or haughty, holier-than-thou, or know-it-all if you prefer those terms) you'll find your audience much more receptive. The bottom line is, even if they're acting like that, it doesn't do to combat such attitudes with the same...that could just be a prelude to an altercation at an event where everyone is supposed to be enjoying themselves and having a good time.
Nothing wrong with knowing your subject, but lecturing is best left to classroom and informative sessions- when dealing with the public mundanes, the less stand-offish you are, the more receptive they will be to whatever it is you're trying to say. Just my humble opinion...and years of experience in giving and receiving training lectures. Its easy to talk when you know what the hell you're talking about, but it may not be so easy to understand if your demeanor puts people off from the outset.