Use the SEARCH function and search for the user name if no callsign.
Use common sense. If it is too good to be true it probably isn't true. If it is offshore, use even more common sense.
Ask for pictures, etc. Do not accept "stock" pictures. Get one with a newspaper or something current in it, too.
Ask for references ... nearby hams, etc. CHECK those references!
Use more common sense!
If everything seems right, there is no reason to be paranoid. There is plenty of reason to be cautious and sensible.