A particular example comes in season 1 episode "The Island" where we have a scene with Clawful's cousin, who has learned that Man-At-Arms is traveling to an remote island to visit his mentor Dekker. Clawful's cousin then uses his claw to make a sound that travels the oceans on Eternia and can be heard at Snake Mountain in a pool of water.
Resulting in the following scene between Clawful and Evil-Lyn...
Clawful: "Hey, you hear that? Some kindaaa clicking sound?"
Evil-Lyn: "It's code. The language of your people!"
Clawful: "Ooohh yeah... Never was too good at spelling stuff."
Which is the lowest point for Clawful's capabilities on the intellectual-department with the show.
Fans addressed this to the show's producer Ian Richter who responded in a Q&A over at He-Man.org:
We were planning a story later in season 2 where Clawful would gain intelligence via some brain tampering from Tri-Klops and almost overthrow Skeletor.And it is a real shame that the second season was cut mid-way because this premise sounds like one hilarious episode for the crustacean villain.