Nefarious information gathering for prospect info... (warning, first post)

Has anyone else considered or currently using some of the recent info leaks (Facebook, LinkedIn data dumps) as a repository to track down hard to get contact information? I've found is useful a few times but have run into calling prospects on their personal devices.

For context; the Facebook leak was a listing of millions of names tied to phone numbers in numerical order. You can either search based on the number (who called me) or search based on the name to find a phone number. *downside here is name searches could return multiples and phone numbers don't have a huge hit rate.

Additionally the LinkedIn leak provided email addresses as well. (often personal email addresses)

I understand some may feel this as crossing an ethics line but in my opinion; if it's legal, it's ok.

Thoughts?