/s takes all the fun out of it. If someone initially thinks I'm serious, someone else gets an opportunity to explain a joke, which is a rare pleasure.
But of course we all know confronting someone directly about their opinion always works.
But of course we all know confronting someone directly about their opinion always works.
Basically, it is now impossible to make a point by attempting to present an absurdly extreme viewpoint in the opposite direction, because too many of us have encountered people who genuinely espouse viewpoints even more extreme. (As well as the exact one you said—no matter what it happens to be.)
If you want to present such a thing sarcastically, you're gonna have to make an explicit indication of your sarcasm (even just a "/s" at the end is usually enough). Otherwise, you're very likely to just be taken as meaning it sincerely.