We've actually found that the ability to provide clear and concise answers strongly correlates with success, so this is a major factor when evaluating founders.
I'm also reminded of my favorite C. A. R. Hoare quote: "There are two ways of constructing a software design: One way is to make it so simple that there are obviously no deficiencies, and the other way is to make it so complicated that there are no obvious deficiencies. The first method is far more difficult."
The same thing applies to business. Long, complex pitches are a sign of muddy thinking and hidden icebergs.