Sometimes I think I get sarcasm, but I am never 100% sure. Other times, I really can't tell at all if someone really means what they say, or whether they are being sarcastic; and then I usually ask outright if sarcasm is what they intend. (they susally seem surprised that I need to ask!)
The problem is that although sarcasm is seen as a kind of humour, it often isn't very funny at all. In fact it can be downright unkind - at least to the person it is aimed at! Other people might find sarcastic remarks hilarious, but often the object of the remarks finds them hurtful or just plain rude. Surely "humour" should be funny ... it should make you smile, or laugh, it may startle, amuse, show you things in a different light. Certainly, you can poke fun at someone in a critical way (think for example at all the jokes about celebrities and polititians in the media, for example,) and this can be very humorous; but it seems to me that personal "sarcasm", aimed at someone you know who might be standing right there in the room with you, is often meant to hurt more than to amuse.
For exampleI have often been the butt of jokes or sarcastic comments about my appearance (I am overweight) usually from other family members. When I have not laughed, but said instead that I am hurt, they accuse me of" having no sense of humour". "Well," I have sometimes replied "I do have a sense of humour! If you actually say something funny, I will certainly laugh! "
Being overweight for example might be unattractive and unhealthy and different from the norm but surely it is not a "humourous" thing, even if true. Making sarcastic remarks that offend someone, and then expecting them to roar with laughter is just ridiculous. If you really must be 'sarcastic", at least be truly witty, and do it with humour, not spite.
Sorry, everyone .... rant now over!
Glenn (edited once for typos)
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'All men dream, but not equally. Those who dream by night .... wake in the day to find that it was vanity:but the dreamers of the day are dangerous men, for they may act their dream with open eyes, to make it possible' (T.E.Lawrence)