When I use google link: for my domain, it show's tons of links that i've never had a link on, are totally irrelevant to my site, and i've never had anything to do with. I check the site and theres no link. I check in the waybackmachine where possible, and no link.
I registered last year in October and hasn't been used before according to thewaybackmachine.
These are not casino links that you just get added to either.. there doesn't seem to any pattern to the topic either.