If Congressmen sound clueless, it is probably because they are. Jeff Stein interviewed the incoming chairman of the House Intelligence Committee, Rep. Silvestre Reyes (D-Tx), and found that he didn't know the basics about the dividing lines in the Middle East, such as Al Qaeda being Sunni while Hezbollah is Shi'ite. Mr. Stein had previously found other members of the Intelligence Committee, Rep. Jo Ann Davis (R-Va) and Terry Everett (R-Ala), to be similarly clueless.
One shouldn't consider congressmen dumb though. They probably know, for example, every major campaign contributor by name, hometown, and dollar amount.
UPDATE: CNN picks up on this story here.
ADDENDUM: Last month, Hugh Hewitt interviewed the candidates for Republican leadership positions and reports that "not a single Republican congressman vying for a party leadership position could name a book he had read relating to Islamic terrorism."