I find that emoticons are downright dangerous, unless you are writing to one person who knows you well. I use them only in text messages and short emails (usually replies, rather than original notes) to friends.
What does :) really mean? Am I smiling, making a joke, or asking you to smile? If we don't have a shared meaning for each emoticon, then I will be misinterpreted. And, when trying to convey emotion, misinterpretation leads to hurt and confusion.
If we want to write to a general audience, let's learn to write well, and express ourselves clearly. Otherwise, I may mean :), but leave people feeling :(!