The only thing that truly mirrors my own personal reaction is “LOL”. If I post that, I have literally laughed and made some sort of noise.
So, no, emoticons don’t necessarily express my facial expression. I’d say emoticons represent what I would do if we were face-to-face. I might smile spontaneously, but I could also smile to show you I mean you to take a comment in a nice way, for example. :-)
Occasionally I’ll make a devilish face >:-) and I’m not sure how to even do that in real life. lol
Emoticons express my intentions whether they mirror my own facial expression or not.