Underestimation of characters due to "goofiness"
I have noticed that many people tend to underestimate characters because of their inherent silliness. I myself used to do this all the time, for example I used to think the Flash rogues were worthless.
However even seemingly goofy or stupid characters can be legitimately powerful.
Take Toyman for example.
At first you think "This guy's gimmick is making exploding dolls, how is he supposed to be a threat to Superman?"
Then you realize he's one of the most brilliant robot scientists on earth, and has created things like nanotech, etc. Also he usually doesn't directly confront Superman but instead uses plans to distract him by going after civilians.
Another good example is Stilt-Man.
He's a guy who walks around on stilts, ridiculous right?
It turns out his stilts are actually a form of powered exoskeleton that gives him super strength, and he has an arsenal of weapons like knockout gas, electrical shocks, laser guns, etc.
What other characters seem silly at first but are actually legitimately dangerous?