Thumbs down smilie doesn't work.
 

The thumbs down smilie gives you a thumbs up image.

Ditto.
 

It did the same to me. :mad:

Non-serious answer: FlyerTalk wishes for all its members to have a positive outlook on life, therefore it is automagically converting all thumbs down smileys to thumbs up. :p

FewMiles..

Serious answer: I think it has to do with the fact that the smiley code for the thumbs down smiley ^_ contains the smiley code for thumbs up ^ in its entirety and vBulletin is interpreting the first ^ as thumbs up, rather than reading the entire ^_ code. This could be solved if they changed the codes to something non-ambiguous, such as :yay: for thumbs up and :nay: for thumbs down.

FewMiles..