I don't consider "opps" as being either a positive or a negative comment.
"Opps" usually signals a slip of the tongue or is said when some minor, accidental thing happens as in my 16 Apr 06 - 09:38 PM post, when I did exactly what my mother told me not to do.
On the other hand, "YUCK" is definitely a negative comment. It signifies my distastes for anchovies.
But truth be told, I've never ever tasted those things.
Anchovies-they smell fishy and they even sound fishy and I don't like fish at all-be they alive or be they dead.
Well, I don't mind Nemo. But he's a cartoon character so he doesn't count.