The information management challenges of data monetisation by David M. Raab via @infomgmt

Organisations must adjust to blurred lines between known and anonymous customer identity information.

I agree with this article - nowadays the data available will contain data that can but also cannot be connected to known data. All organisations need to have a strategy on this data . I recall in the past the unknown data was ignored and deleted.  Nowadays this is missing a valuable source of information and potential customers.  My advice would be to have default values for all fields so that you do not have any empty fields and do not find that joins will not work or have to be outer ones.  That way you can use everything as much as you can.