Amos at 2011-05-24 23:37:53:
I'd say the answer to the question is Yes.
As a script reader, I once feverishly recommended a dramatic writer who wrote action and dialogue beautifully, but whose spec was far too expansive relative to commercial appeal to be made. That writer is currently working a fair bit.
The funniest spec I ever read was largely set in a fantasy world that would have made it prohibitively expensive (we're talking well over $100 million to be done decently). It was hilarious. Four years later, I can't find a trace of the writer.
Your pitches may look great, but you have to at least come near the strike zone.