In bridge,should a responder devalue her hand if short in opener's suit?
"Bidding your suit" typically means 4 or 5 card length.  Because of that, I would expect the bidding to go more like this:
Partner sitting there with one card in that suit would then respond with their suit (4C in this case), which denies support for your spades and shows that clubs is their best suit.  The new suit bid is forcing, so it's now back to you to decide what to do.  Partner doesn't have your spades, but you can rebid them since you've got 6 of 'em.  If you really want to you can make a NT bid, since partner should have your one weak suit covered.  Whatever you reply with, partner has a chance to correct if they're significantly over the 9+ they've promised.  With the length you've got, a spade rebid is valid and 4S should be a solid contract.  After that you each have to decide if you're going to go to Blackwood and look for the slam possibility.
Sure there's interest in slam, but there's no 8-card fit.  And the bidding should show that.  Someone has to make the call as to whether or not to go there, and at what point the bidding stops.  That's whoever makes the Blackwood bid.  With an even split, you get it.  Without, you don't.  As long as the player making that bid understands the risk involved and wants to go for it, it's all good.
If both of you understood the danger you were getting into and the possibility of a bad split ruining it all, then I can't say you've got any problems in the bidding.  If on the other hand someone thought the slam was solid, then I'd say that your bidding needs to be a bit more descriptive.  

In specific though, YES, there are two specific situations where shortness doesn't give ANY points:
1) In the trump suit
2) In a NT contract  

And that's one of the more reliable rules in bridge.  8 )