Webcams are so cheap now days
"Is it morally ok to be rude/disrespectful to someone who you perceive to be less intelligent than you?"
The simple answer is no.
The complicated one, is it depends on the situation, and they are often unique.
What annoys me here on the forum from time to time, is rarely that I think someone is stupid (although let's face it, we've all read some facepalm worthy material), but rather that they are lazy.
That they demand a simple answer to a complicated question.
That they continue to ask questions, to which answers are
easy to find.
That they in turn perceive as rudeness, an answer that is simply short/terse, and equally as uniforming as their question.
To a person who is simply lazy, I will just stop responding. To a person that becomes rude, I'll use nice language, but no longer feel any obligation to actually be nice.
To take Tmack analogy - of course it's easier to point out the bathroom, but would you really want a customer to whom you also need to show where the Bar is, or the tables, or the back door? I guess yes, if you're a paid host, but none of us here are.