It's implied Mertle may be a moron. Considering she gave silly answers that were obviously not correct; from Teresa, whom was made silly by Spike.
Spike has a true place as emotional support hugger in therapy groups; though he has to wear a special suit to avoid poking others with his quills
Jumba is revealed to have his seriousness/intelligence be 10xs the amount of humans and some others. 1% of his intelligence is comparable to 100% from Stitch.