1. I think a Blizz employee will investigate by the first report - no mather your history.
2. I think a Blizz employee will screen your computers memory to check what programs you are using.
3. I know Blizz checks IP, for example: When I got banned and made an appeal saying I was not at home, they said my account was logged on the same IP, I always use, at the moment I botted.
4. I think a Blizz employee can see if you use HB or any 3rd party programs.
5. I know a Blizz employee need to have proof that you are using HB actually for and in WoW, and file this proof.
6. I know a Blizz checks by lifting your char up and letting it drop from in the air to the ground so you get fall damage, and to see if your char instantly eat after., or drop your char into a pack of mobs to see how your char will react. I know this for 100% because a GM once showed me 4 years ago, a few ways how they investigate.
7. I think a Blizz employee will flag your account after they have proof you have been botting.
8. I think the chances are there that if you are unlucky, a GM might keep an eye on you and will check for you another time.