Sometimes, sarcasm is best when served ambiguously, too -- but my point isn't really about bad messages or bad receptions. It's just about the simple fact that smileys are insufficient, even utterly pointless much of the time, because of the fact they've never been well-designed for the purpose some people claim they have and have since their inception been co-opted by contrary uses so thoroughly that any lingering value they might once have reasonably been imagined to have has evaporated.

Misunderstandings happen. Either accept it or be incredibly explicit about your less-than-literal meanings. These are the reasonable options. Throwing a likely ignored, colloquially meaningless smiley on the end of something as if that solves all problems is definitely not reasonable, and pretending the opposite is true in some kind of extended defense of smileys as the One True Cure for Misunderstanding (as some people do) is not just unreasonable, but durned near sociopathic or delusional.