Actually, it always bothered me that DC, at least since Byrne and probably before, forgot how smart Superman should be.
Think about it: On Krypton, both his father and grandfather were the greatest scientists their world had to offer. His father was able to deduce, when no one else could, that Krypton was going to explode. And his father didn't have superpowers. Are we to believe that Kal-el didn't inherit at least some of his family's brainpower?
Furthermore, when you consider some of the creative ways that Superman has used his powers over the years, he demonstrates very deep understandings of chemistry, physics, biology and other sciences. For example, in his battle with the Elite, Superman didn't just hit them all until they fell over. He used his powers to attack them in ways that required him to figure out things about the Elite's anatomy that would have stymied most forensic teams.
He's also demonstrated an advanced ability with robotics and other technological marvels, and can operate various alien technologies with ease.
Someone with that much brainpower is going to be able to do some damn fine detective work.
