Those search ads you see all over the internet are the same as typing someones name into goggle. All their doing is getting paid to do it for you. If their were 50 Rob Singers listed you would get all of them. SS numbers separate the Men from the Boys when it comes to searches. Posting someones SS number is a definite NO NO. A license ID number could also go a long way in a certain specific state, but not help with financial information.
As a business owner it is important to have permission from an employee to do a search. The more personal information you could enter into the search the more information you will receive. Financial information usually requires a SS#. Having a signed stipulation agreement prior to search will usually protect you.
There are all sorts of protection laws including I think the 4th amendment to protect people when it comes to different types of searches. It's a grey area and should be approached with knowledge and caution. A cop searching a person without proper cause usually gets charges dismissed.
P.S. Any information anyone including Maxdepends and Kiwlj could get from cheap search engines on the internet most likely are garbage and un-confirmed. Employers for example pay serious money for serious search engines since that information could be the difference between getting hired or not, and potentially lead to a court case.