Scandinavian Defense with 3.c4 I've recently played some games as Black that opened like this:

[White "Opponent"]
[Black "Me"]
[Result "*"]
[ECO "B01"]
[FEN ""]
[CurrentPosition "rnb1kbnr/ppp1pppp/8/3q4/2P5/8/PP1P1PPP/RNBQKBNR b KQkq c3 0 3"]

1.e4 d5 2.exd5 Qxd5 3.c4  *


c4 seems to be a very uncommon move as opposed to Nc3.  But it doesn't seem bad at first glance - it allows the knight to go behind the pawn when Nc3 is later played, and grabs some central/queenside space.  It also forces the queen to move (although 3.Nc3 would also have done that.)

How do I refute this variation?  Or is it perfectly playable?

My opponent and I both have USCF ratings in the 1500s, if that matters.
This is what I try to accomplish as white, but I play Nf3 first.
Although your can't take advantage this early, there are good moves depending on your temperament.

Qe4+ forces Qe2, else a pawn hangs, and the trade of queens.

Qa5 pins the d-pawn which gives you the opportunity to get in c5 (e5 is more drawish) and get a central majority.

With a normal game continuation, that is Qa5 => Nf6..., the d-pawn is slightly weaker as white can't play c3 to support it.  

Just the opinion of a 2000 player.