glib [glib] adjective, glib·ber, glib·best.
1. readily fluent, often thoughtlessly, superficially, or insincerely so: a glib talker; glib answers.
2. easy or unconstrained, as actions or manners.
3. Archaic. agile; spry.
I'd say glib describes just about every politician.
Well, maybe not George W. Bush...at least not the "fluent" bit.