Agnostics are often well-educated, and even more often do they see themselves as such. An agnostic, by virtue of their belief, typically sees themself as a very skeptical and critical person, and indeed, they usually are. They are often more intelligent on average than those who believe they know things, or at least, so the stereotype goes. Because of this, they often develop a sense of superiority, by which they can logically and rationally transcend the arguments of less-intelligent theists, who tend to be the most vocal ones.
An agnostic esteems above all else the scientific method. It is the infallible absolute of the agnostic. Everything must be empirically demonstrable to an agnostic, or it cannot be known to exist. A typical argument an atheist would use against a theist would be: "Since you cannot prove the existence of your God, how do you know that he exists?"
An agnostic attempts to apply empiricism to absolutely every aspect of reality. A thing does not exist unless it can be "scientifically proven". A modern understanding of science is the typical rhetoric of the agnostic.
Agnostic: "I do not, because it is impossible to prove the existence of God. In fact, I do not believe it is possible to prove the existence of anything, as everything we've known is a product or our subjective consciousness."
Theist: "Are you sure?"
Agnostic: "Yes, I am 100% sure."
Agnostic: "If a thing cannot be proven scientifically, there is no way to know that it exists"
Philosopher dude: "But you are assuming the existence of knowledge, which in itself is a totally abstract concept that is entirely unprovable by those means. If you are to apply the scientific method to every facet of knowledge, with our current understanding of perception and cognition, it would be impossible to trust your own senses, and everything would be unprovable, and hence, you could know nothing at all, including the validity of the scientific method."
Agnostic: "Any ideas of yours cannot be empirically proven, so I need not listen to you."
Philosopher dude: *facepalm.