The internet is for learning from each other! New people! New perspectives! Intelligent, constructive conversations! Critical thinking!
Was that sarcasm? I can't tell
Absolutely not.
Was that sarcasm?
I know I'm not the only person with this problem. Sarcasm cannot be communicated across the internet in words. It relies on context, facial expression, tone of voice and inflexion to be effectively understood by the recipient. None of these things, except maybe context, can be adequately represented by the written word.
There's no sense in aruging that people 'should' know when someone is or is not being sarcastic because people are different, with different genetic makeups, personalities, experiences and senses of humour. If I find something funny, its odds on you won't.
So! That is the problem. Fortunately, I have devised a solution. Ironically enough it was suggested to me by one of my favourite TV shows, The Big Bang Theory.
Why not use a sign or some sort of visual symbol to denote sarcasm?
Check it

How effective is that?? Now Sheldon knows that Penny is being sarcastic, so he can respond in an appropriate fashion.
Now I am not calling for humanity to carry around sarcasm signs at all times and use them in real world interactions. That would destroy the spontenaety of the humour, which usually intensifies when one person in a group 'doesn't get it'. As I said above, the problem is not with real world sarcasm. The problem is the internet, and the textual nature of the interaction.
What I am suggesting is that from now on whenever you are being sarcastic in a post, use this happy fellow

to help your fellow posters along.
That is my idea, if you have any better please do share them.