Whats the problem?
With any mobile device you are capable of being tracked, don't want to be tracked, don't carry a phone or other electronic mobile device.
I usually switch off Bluetooth if I'm not using it and sometimes even WiFi if only because on the average smartphone the battery lasts a lot longer, this feature would be handy for the museum guide scenario though.
Companies dream of being able to hit us continuously with a stream of targeted ad's but I think the reality will be that they will just very quickly annoy people and these features will be turned off by users or they will get enormous adverse feedback from satisfaction surveys.
In the case of Government's etc tracking us, well they already do have more than enough ways to track us without this, there have been a number of cases where people have been convicted based on ordinary mobile phone triangulation data placing them in locations where they said they weren't, and if you really get on their radar even having no connected communication devices at all won't save you (as Osama Bin Laden found!), if it get's to the point where you have a team of spooks and a satellite dedicated to you then Bluetooth is probably the least of your worries, this is in the same category as store loyalty cards in privacy terms.