Gentlemen,
My brother-in-law is a retired private investigator. He ran a franchise system of shops in New Mexico, including Albuquerque. He is the author of "Serious Surveillance for the Private Investigator." If you really want to check up on someone, I suggest hiring a private investigator, as they will have access to all of the best background sites, and it would be cheaper than subscribing to all of them.
The usual sites include checkmate.com, truthfinder.com, and idtrue.com. They are going to cost you maybe $35-$50 per person for a crude summary. Many of the sites sign you up for an monthly fee, and you have to go through the hassle of extricating yourself from the billing.
The summaries often have some inaccuracies. For example, if you plug me in on one site, you will get descriptions conflated with my father, who had the same name. While I appreciate being listed as having owned property I did not own, I also do not appreciate being listed as 86 years old. I wind up with assets and debts that are his, and he died 15 years ago. People do often have more than one social security number in real life, which really messes up the algorithms.
Despite Argentino's comments in old posts, people can scrub themselves, which has some real effects. Where these sites are most valuable, in my opinion, is that they provide, for the most part, accurate listings of siblings and related people. Those people can be contacted or interviewed regarding the actual target, and more will be learned from those interviews than what one reads from potentially flawed information summaries.
It also occurred to me that one reason you cannot publicly post or use these summaries for credit decisions is that things like having your record purged of a legal snafu may not register or catch up in real time with the expungement. So a legally expunged record may show up as not expunged. While it's useful for others to know about these things, it defeats the purpose of the expungement. The expungements are legal and supposed to be opaque.