For me the biggest "dog that did not bark" was real estate agents. I used both a separate email and VoIP number to my main one, which was handy as it meant I could switch them off at times when I didn't want to deal. I got plenty of calls and emails during the process, but as soon as I made a transaction, crickets. To the extent that I think they must share a negative list. I guess they value their own time and know that once you made a transaction, you're not going to be making another soon. Surprisingly this continues to hold, no "are you thinking of moving again" now it's been a while