Don't flame me for this, but I think you guys are making a huge assumption here.
First, you're assuming that the average passenger even notices when you walk by them. The average passenger is too busy trying to get to their gate to see others in the airport as anything other than moving pylons to get around in their quest to get where they need to go. On top of that, if they have rugrats, they're busy trying to keep their rugrats under control.
Second, if they do notice, you're assuming that they
- Don't have earbuds in all the time themselves
- Think it's unprofessional to do so
By all means, if they tap you on the shoulder and ask you a question, answer it even if the answer is "I don't know."
But from one paying passenger's perspective, I'd say relax about the earbuds.