I found some very intriguing/disturbing things while I was paying for full access on Ancestry.com. Those genealogy sites have powerful searches over a lot of public-records databases if you pay them enough. So naturally, I investigated myself.
One of the biggest mind-benders was finding a person with a string of addresses going back 25+ years. Now I've lived in this area for 27, and for some reason, this person's addresses all coincided with mine. They had lived near every residence I ever had; they lived within a stone's throw of every clinic, every church, my college, every place I had a relationship with. One such person's "last known address" was an exact match for my previous address: apartment number and all. I found a profile on Facebook but it is unknown if these are real persons, or fictitious entities in the public record for some purpose.
Then, I found a person who seems to be real (has a Facebook profile with photo, lists a real place of employment, etc.) She shared my exact surname and had a given name that matches my ethnicity. She lived at the same street address for a long time, albeit a different apartment number. I was receiving mail for her.
At some point, this phantom wife/sister was conflated with me in the public record. Obviously someone got her unit number wrong if I got her mail. But my phone number was eventually listed as hers. She has found herself in debt, and is sometimes referred to a collection agency. I've gotten no less than 3 separate inquiries for delinquent debts, that are clearly not mine, that start coming through because her contact info is utterly conflated with mine, and apparently no valid, current info is giving them any leads.
The crazy thing I learned last year is that a collection agency doesn't need to divulge any details of the debt they hold to the person they contact. It is incumbent on the contactee to verify whether they reached the wrong person. I began following CFPB instructions on disputing the debt, but the collections agency clammed up and refused to answer any questions until I answered theirs (registered on their website, divulged a lot of PII). However, the joke's on them, because it is very easy to review credit reports and determine whether a debt is or isn't on my own record.