Look, that wasn't a tone problem, it was a content problem.
Whether or not ed was sarcastic or complimentary, nevertheless his comment made people realize that Spolsky could stand to gain financially from the article. Putting that on the radar (even if it was in the form of a compliment) was a hit to Joel (even if he didn't intend the article as PR).
All the smileys in the world wouldn't make that content issue go away.
The reason Joel interpreted it as an attack, though, is because the commenter used words with negative connotations, like "disguise". I would have written the post with different words, and I bet Joel wouldn't have gotten defensive in that case. It would be the same content, but less accusatory tone.
So while using ":)" is helpful, so is using words with positive connotations if you're trying to be positive.
Whether or not ed was sarcastic or complimentary, nevertheless his comment made people realize that Spolsky could stand to gain financially from the article. Putting that on the radar (even if it was in the form of a compliment) was a hit to Joel (even if he didn't intend the article as PR).
All the smileys in the world wouldn't make that content issue go away.