I used to bot on multiple accounts (about 9 at a time) since TBC until I stopped playing WoW at the end of Cataclysm. And I did this on my own accounts following just a few simple rules. Since Blizzard's Warden and later Warden 2.0 were completely useless because good bots didn't use any memory injections of some sorts the only way to detect a bot was due to the character's behavior. Even with greatest efforts Blizzard isn't able to detect bots at all, except for those with noticeable behavior like those in battlegrounds.
I only used bots when I was sitting infront of the PC, whenever I was somewhere else in my flat I turned on my speakers in case I get a warning sound and run immediately to the PC.
I never used bots in battlegrounds, this is plain stupid. I enjoyed battlegrounds myself a lot and accumulated about 300k HK across several characters.
I sold my stuff only in private to people I know, those were redistributing farmed stuff just like in the drug business. I never sold raw materials on the AH, only produced stuff across several of my accounts undercutting each other to make it look real.
There was/is some sort of a botting community on my realm and we shared materials with each other to maintain our own supply and demand.
Having 3 screens on the desktop like I do allows you to run 8 bots without further concern while doing arenas or raiding on the middle one, this was my case.
TBC was the greatest time of all since the gold price was pretty damn high. The bots during that time weren't as good as the creme de la creme today, but they (it) did their job. I was selling my gold personally to customers who approached me and if I didn't have anyone I always had the Chinese on my side who paid less but they bought everything I had. Since time is a very important thing in this business I didn't care who I sold to. I had no account banned, I never received any warnings and I made enough money to sustain atleast 9 subscriptions, buy high-end hardware every couple of years and the list goes on.
The moral of my story is the fact that you cannot suppress botting. You have this in pretty much every game nowadays. It's the same on the streets. You cannot completely stop criminality because this is a part of the living organism we call society. Well if Blizzard would care just a little bit more about their customers, they could just start getting those people botting in battlegrounds, this made me rage several times aswell. There was a heavy banwave during TBC and the renowned Pirox bot which banned so many people. I miss those times.