And then you get people like me, where "I like being ignored" is not sarcasm, but a commentary/personality preference related to disliking a cultures obsession with fame and popularity and struggling to think of anything worse than being recognised/constantly under surveillance.
As you said, context is everything. It is literally impossible to detect sarcasm reliably with only the sentence in which sarcasm is contained.
There's also a blurry line between sarcasm and lies. I'll often say things that are patently untrue to people with the expectation that they know the truth (and me) well enough to get that I'm not serious.
For instance, to my sister:
"I hate you." - sarcasm.
"I've already told you many times that I hate you." - obvious lie, maybe sarcasm?
As you said, context is everything. It is literally impossible to detect sarcasm reliably with only the sentence in which sarcasm is contained.