@kamaa_......for phone models e.g nokia 6310,8910,moto v80 you gain unauthorized access. for most other models however the first connection must be authenticated..........e.g. a popular campus style in use.....a guy comes pretending he wants a wallpaper or a ringtone from you and once the phones bond,he can access later at will as long as the bluetooth is on and within a 20m radius.
don't expect anyone to act like your favourite grandmother in wanting what's best for you.