Generally, I don't delete my comments. I've seen several posts on AU where people's comments don't make sense, presumably because previous posters deleted their comments. It's worse when these comments don't reference previous comments (making them seem like wild tangents).
Deleting comments seems to be more prevalent on AU than other Stack Exchange sites, so I'm wondering what is the custom here for deleting comments?
The only reason I can think of to delete a comment is if it was no longer true (ex: pointing out flaws in an answer that have been fixed). However, this can be confusing if others in the discussion don't delete their comments.