I've not had my account punished in any way, although I did receive a ban on an alt I got from a particularly shady dealer - (I think you can guess why).
I'm still pretty new to HB but with such a large community it seems clear that the bot itself is undetectable, or else why would we still be here?
That leaves the only remaining factor in being banned to the user. If you are doing things not humanly possible - farming round the clock, performing feats that require superhuman reaction times (particularly when under scrutiny; high level pvp/raiding) you are tempting fate.
In my opinion variety is key. If you do a bit of archaeology, then a bit of farming, a bit of pvp then a few quests you will have to be a lot more attentive to your account, but your activities will seem a lot more human and thus less suspicious. That being said, this is just my logical sounding shot in the dark so feel free to correct me.