Take this phrase:
"That's what you get."
The wording implies that it could be used both positively and negatively, à la 'what goes around comes around.' That is, if I do something good, I 'get' rewarded, and if I do something bad/dumb, I 'get' punished.
And 'getting' is normally considered a good thing, because you've received something- does that make derisive uses of this phrase sarcastic? (Because the literal implication of the verb 'to get' is a positive one.)
Also, despite the fact that it could, semantically speaking, be used to either praise or chide someone, I don't think I've ever seen the phrase used in a positive manner. The wording suggests that you got a reward or obtained something, but it seems to rarely be used that way. Why is that?