In reply to:

One thing I have noticed is that people who (a) don't understand irony, but (b) DO know what it is and who the people are who apt to use it, stare at you intently when you say something that they really aren't sure about.

Reminds me of one of my favourite remarks from Jane Austen:

Though nothing
could be more polite than Lady Middleton's behaviour to
Elinor and Marianne, she did not really like them at all.
Because they neither flattered herself nor her children,
she could not believe them good-natured; and because they
were fond of reading, she fancied them satirical: perhaps
without exactly knowing what it was to be satirical;
but THAT did not signify. It was censure in common use,
and easily given.

Sense and Sensibility Chapter 36

Bingley


Bingley