Did i ever tell you guys the joke about the priest, agnostic guy, and a philosopher typing about irrelevant things sparked from a simple 3 box cartoon published 10 years ago to prove a point to other people on the internet that they don't even know? I didn't tell you, oh okay then.
Questioning everything does not necessarily lead to agnosticism, and being arrogantly smug because you believe so does not make you right. There were many great philosophers who constantly questioned everything, yet were not agnostic; Socrates comes to mind.
However, you are right that often scientists forget that they need to question what they are doing; my problem is that often they become so involved in attempting to prove a hypothesis that they fail to take into account other possibilities that would also explain their observations.
This reminds me of the cartoon episode where Dogbert argues about all the flaws in the theory of evolution so that Dilbert will let him have the TV remote. Sometimes it seems like scientists *believe* so strongly in "science" that they forget what makes it work: questioning what you *think* you know. Sometimes all it takes is stepping back and getting a fresh perspective on the big picture to begin questioning how much we really know.
But then, people tell me I question everything too much. I guess that's why I'm agnostic. Heh.