@ArenMook
While padding does fix any vertical alignment issues, it's also making the backing sprite unusable for cases where it is also used within a normal UISprite.
For example, I have to add -12 to the top-padding of a larger sprite in order for it to align correctly (as an emoticon/symbol) with the rest of some text. However, if I want to then use that same sprite in a UISprite (not as an emoticon), the top edge is now 12 pixels distended on top.
It seems the only solution is to always use UILabel (and not UISprite) to display that specific sprite, after the padding has been altered for an emoticon.