Do you use some kind of whois privacy? If not, all your contact details are online, publicly visible anyone to who cares. If a whois command is installed on your system (Linux, macOS), open a terminal and type: whois example.com Replace example.com with your domain name. You should see contact information for the owner of the domain.

There are dubious services that scrape that info of newly registered domains and offer their services.

Edit: For some TLDs, whois privacy is not allowed. Depending on your TLD you may not be able to activate it / use a privacy service. You could always enter incorrect information but in a dispute you might lose your domain.

If you're not using some whois privacy protection, they're literally giving it away. They all do, though—that's how it's supposed to work.

http://whois.domaintools.com/cscrunch.com

Edit: Ah, I missed the part where you say you understood what whois is.

So, to answer your other question—yes, there are many services that will sell you changes to any whois entry.

If you try Godaddy you will get called by a salesperson who thinks that registering a domain name is a life changing event. I tell them, "Look, people ask me how many web sites I have, and I tell them I don't know." It's just like John McCain didn't know how many houses he owned.

To answer your edit: There are services that sell lists of newly registered domains. Not sure how they create these lists in the first place. They probably hook themselves into the DNS and keep track of changes.

I experienced the exact same thing. Their customer service rep directly denied it.

Three or so months after listing it I still receive a call like this once a week or so.

I have multiple domain names with NameCheap, some with privacy guard and some without, and I have not experienced this.

Me neither and I have more than 10 domains parked with them

Welcome to 2017