This guy rang our doorbell this morning. We didn't know who he was, and a houseguest that saw him from an upstairs window said not to answer the door (exact words were "he looks menacing"), so we just didn't answer the door. Two minutes later the phone rings. The guy on the line said he was outside...something about a request for an estimate on air duct cleaning. We hadn't asked anyone for an estimate on air duct cleaning, but we did just have a guy in to look at the heating system, so we thought it could be related somehow. I said we'd call back if we find out someone did mean to call about air duct cleaning.

He's called back twice since then. I'm not sure what to think, but the fact that he was just outside, ringing our doorbell without us even asking people for referrals, is pretty odd.