From the webcomic: Ok, so it's pretty common and accepted in the webcomic that anthropomorphic animals exist and live among humans. So why is it whenever Art calls the police or an insurance company, they treat him like he's nuts whenever he mentions an anthropomorphic animal is the reason for his calling?
He saw Boogie-Men.
We may also be dealing here with a Calvin and Hobbes style of "dual perception," in which Art sees anthropomorphs and the rest of the world just sees humans. However, that's a shot in the dark: the strip itself hasn't shown any evidence to back the theory up.
So the aliens of the last arc are peaceful. And yet they saw fit to abduct people, drug and publically humiliate them. Uhm, couldn't they have simply told and shown those people the truth like they eventually did?