Could anything be done about post subject lines being messed up when editing a post?  For example, not only are subject lines often truncated, the emoticon on the original post is removed.  

It would be wonderful if when editing a message, the subject line would be carried over from the original, allowing edits if desired, and we were allowed to update the emoticon if we wished.

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...subject line has a quotation mark, it will delete all text after the mark, thus making the line truncated.

You can still recover it by starting to type the same first words of the subject line.  There is a drop down which contains subject lines which similar opening words.  Select the one that was truncated/messed up and it will appear on the subject line again.

I rarely use emojis but I don't see why they can't be changed to a different one or "none" when modifying your post.

Yes, you can edit the subject line to restore the truncated text.  You just need to notice the subject has been truncated.  Maybe I'm the only person who forgets to check that sometimes.  

I don't see any way when editing a post to change the emoticons, as I do when creating the post.  Interesting that you have that option!

...truncated and I have to go back and modify it again.  Here's another tip - if you don't want everyone to know that you modified a post three or four times, you simply delete the note added that says:

"-- Modified on 9/6/2014 11:44:34 PM"

That way the note only appears once and people won't say: "Why did it take that idiot four tries to put up a post?"