Should I continue to thank someone who holds the door for me, but never makes eye contact or say anything after I thank them?

Do they not want me to say anything to them? Is that why they avoid eye contact?

There's this dude I'm considering as my roommate.

Problem is, while using public restrooms, I've seen him miss the bowl quite a few times, AND, on top of that, not wash his hands after doing his business.

You think he will carry that behavior into my apartment?