I would not let any stranger insert a cable in any of my devices.  I would not use a public charging station either.  Hell.  I do not even use public outlets, I bring my own Power Bank with me and run my devices using it.  But even if I was not this paranoid generally, I know I would still not let some body else insert an USB in my phone.  People use USBs to transfer their private files to their computer, how do they not have this little common sense?