One thing I don't trust about sites like those.. Log files. You enter a phone number and find it's location, somewheres down the line.. the system is going to store a logfile.. and if a hacker by some odd chance, knew you're phone number and or someone close to you's phone number was entered into the site like that... you could easily be found. Now.. I'm not 100% sure, if that site and or relative sites will keep log files, but to stay on the safe side.. I wouldn't use them.
