If characters are needed to be written dumb just to force the plot forward and/or artificially make the other characters appear better, then it's bad writing; A Dog and Pony Show had plenty of it, ranking this episode somewhere between average and bad.
Also, being "clever in short bursts" doesn't cut it, either. It just leaves room for potential, only for it to be lost in the shuffle. There's a difference between clever and stupid and clever and smart.
