Ok so atm i am completely sure that blizzard is scanning your PC to see if you have third party software installed or not...
I was only like 99% sure until yesterday,but when i tried to make a new account this morning i was made to accept something like "Blizzard will monitor your PC bla bla to prevent unauthorised bla bla" i forgot what it exactly said....
This totally explains the huge ammount of ban reports lately.
So im thinking that a decent way to bypass these scans would be to install HB and everything related on an USB stick or something,and run HB from there,i dont think Blizzard will/can scan external drives