You can't sell them. At least the ones you get for doing quests you can't sell. The ones from the IM I do not know.
Scorpio 2
Felixoo7
http://wlodb.com/topics/2116 <-- Fishing!!!
http://wlodb.com/topics/2325 <-- Monsters!!
http://wlodb.com/topics/3690 <-- Economy!!!