With mine the phone (not iphone) the computer generates a code that you have to put into the phone for it to sync.
I guess the other devices you see are your neighbours.
You could always try and search for devices from your phone when you are in say, the pub, just to see how many devices are on and what they are called. If you were near me and tried it you would find my phone is called by a "colourful expletive" Its quite "interesting" how many devices are actually on.
Above are my opinions Below is my signature.
Would you hit a nail with a shoe because you don't have a hammer? of course not, then why work on anything electrical without a means of testing Click Here to buy a "tester" just because it works, does NOT mean it is safe.
most bluetooth stuff has to be told it's connecting via pairing,
on basic stuff that's normally a button you hold down till a lights flashing.
unless it's paired with your pc / mobile then it wont talk with it so no danger.
as the guys have said, to make the more complicated devices invisible when searching, turn "discoverable" off
(windows does this auto after 2 mins normally now days)