I've got conclusive proof. They live on my block. For $14,000 in cash (while the $8000 tax credit was available. Do the math.). You can imagine the shape the house was in at that price. I knew we were in for a wild ride when they didn't bother with major renovations (I mean installing walls) before they moved in.
Part of the reason I'm sure they are aliens is that they are immune to the sounds and behaviors that any human simply cannot tolerate. First example, I can routinely hear their children yelling in a way reminiscent of horror movies. Through two sets of closed windows. And it's not because the parents are beating them; that's how they play.
Second evidence is their dog. Which barks all day and all night, indoors and out. Any red-blooded human would have disappeared this dog weeks ago. Every time we go over to complain about the dog, it mysteriously ends up inside through the back door despite a notable lack of humanoid presence at the front door. Question: How can their super-sensitive alien hearing detect that we're coming over, when they are deluged with noise non-stop?
I can't really figure them out. They seem nice enough, but I have a really difficult time reconciling their overt niceness with their incongruous, complete disregard for people living nearby. Maybe I should chalk this up to punishment for all the nights we partied loudly until the wee hours when the previous neighbors had a house full of young children.
That's probably fair.