Maybe reviving a dead post, but here is my experience.
Friend and I co-invested in 3 keys, picked up a second account, transferred off a druid for mining/herbing and went to town. 4 days 1-80 questbotting 4-8hrs 90% monitored, with BoA gear. Spent the next 4 months just farming herbs and nodes. Not quite as profitable as expected because AH is always saturated so ended up finding a few dedicated buyers for about 10% less than AH, but means stuff always sold. Friend was also using prospecting to shuffle on his main. Eventually I let him take over the 2nd account because I was bored and fishing was making more money with fish feasts on my main. He got the account banned in 2 weeks for botting 12-20hrs per day, probably 50% monitored. He also got another friend's account banned for 1 year for doing the same thing. When he tried to fight it they replied with something along the lines of, "you went to the EXACT same spot 12000 times. kthxbai".
tl:dr--I've been using HB since ICC and have never gotten banned. I received a 3-day "suspension" for manipulating the market when I got bored one week and mined the crap out of everything. I've questbotted 8 characters from 1-85 and am currently questbotting 85-90 on them. I would like to think that the reason I don't get banned is that I have a pretty tight LogMeOut setup with sensitive settings, meaning stuck/inactive more than 2mins = logout, players following more than 3mins = logout, stuck more than 5x = logout.
To the guy who has leveled in BGs and thinks questbotting is the key to getting caught: I doubt it. As people have said, BG bots are easily noticed, especially with everyone using the same profile. Questbotting seems to be the least obvious, especially if you're monitoring enough to respond to whispers/guildmates. I just tell guildies that I shut off chat or that a friend is on my account and they're shy. A couple know that I bot, but they never know when because I monitor it so much. If you're really worried get an addon like rarekiller that makes an annoyingly loud noise every time you get a whisper.
Going strong since ICC with HB (yay lifetime membership!) and not regretting a moment of it. But I also don't make 15k/day.