As pointed by @MichalMalkowski ; Vienna Gambit is sound, though it may be a bit too sound that it is never accepted, or in other words it is best for black to not accept it.
Queen's Gambit is not a gambit.
If you really thinks so, than Vienna Gambit is not a true gambit too. Black can't really afford to accept the pawn - white will either regain the pawn with a nice plus or crush black's position. White takes no risk here too, at least no other then one of black's forcing a dry equality. For this reason Vienna gambit is much weaker then queens gambit -the later es equally good accepted and declined.
It is funny thing with those gambits. If a gambit is "too sound" people no longer consider them a gambit. If they are too unsound the call them blunders or hanged pieces. Note - most time a player loses material, he gets a tiny compensation - in form of enemy pieces entering odd squares, leaving their natural posts and tasks. It takes time to consolidate back, which can be occasionaly exploited. In that case, the blunder becames "a brilliant exchange combination" :-).
Personaly i absolutelly disagree that the queens gambit is not a gambit. An opening sacrifice is an opening sacrifice. That one is simply temporal. There is assumption that the sacrifice must be for long or be unsound, which makes vienna, scotch and queens gambits "not true gambits".
As pointed by @MichalMalkowski ; Vienna Gambit is sound, though it may be a bit too sound that it is never accepted, or in other words it is best for black to not accept it.
Queen's Gambit is not a gambit. Yeah there are lines that white pushes for more compansation and black can hold the pawn, but these are very sidelines. I am unsure whether they are good or not but my point is Queen's Gambit is not really a gambit.
Well it is possible to compare it with Budapest Gambit to show my point. In Budapest Gambit, white can hold the pawn if they want, generally they dont hold but they can hold. On the other hand for Queen's gambit, black cannot keep their material advantage after 3.e3, for example.
Not a gambit, but, I disagree with Scandanavian being unsound. White generally have an advantage due to center situation (w:e4 b: d6) but it don't feel completely unsound.
I have no spesific idea about the line shown by @Marco (I remember that variation having a name but not sure on spesific name).