I definitely believe that this smile
's description should be changed from
frown to "sad" but I really don't believe that the whole range of our twelve smilies need to be revamped with new definitions as they seem to fit pretty well to me (though I do believe that the "eek" smiley has been used for excitement as well as for shock).
As for a convention -- I think that would be a...limiting...idea. It would be difficult to have a convention to determine the meanings of each one. Take, for instance, this smile:
It could be used as happy, but I have also used it as a term of politeness in dealing with people I do not want to offend but whom I must deal with anyway (alas, one of the problems of mod duty). What gives? Happy, or the polite smile that people wear when dealing with people who are constantly breaking the rules, etc. Then there is the cool smiley
: cool, or smug?
What I'm trying to say is that often some smileys have a double meaning. Hence, if you do not want the meaning of your smiley to be taken awry, make sure that the context and style of your smiley agree with the use of your smiley.
Readers of smileys should look at context and tone. If it sounds nice and they think the smiley is sarcastic, then just assume that the writer used a poor choice in smileys. On the other hand of that, if the writer was being sarcastic then he certainly should have shown it in the context and style of his writing.
It's the flip side of the coin: a smiley enhances what you are trying to say. It does not say it for you. Likewise, your writing defines the meaning of the smiley.