Part of the human expression of disgust includes thought terminating cliches. Imagine how the average person would talk about a race of bug-like aliens, no matter how advanced they were. It would be a dismissive kind of 'ew, gross'. The humor is in seeing other beings reacting that way to us. I don't think it's supposed to imply the aliens are some kind of flawless geniuses revealing the true nature of human beings.