This method requires two people. Yourself and someone you can trust.
This is what my friend and I do:
1. My friend plays WoW like a normal player during the day.
2. He logs off in Orgrimmar at 12:00 midnight.
3. I log onto his account and travel to the lost city of tol'vir instance and fish bot over the night as we both sleep
4. In the morning I wake up, port back to Orgrimmar and list all the items/transfer to my own account
5. I log off in ogrimmar and my friend logs back on and repeats step 1 and so on.
So what this does is basically simulate my friends account being hacked. When GMs look at the logs they see a normal WoW player who runs instances, quests in the day and logs off at a reasonable time. Then they see someone else log into the account late at night with a different IP and bot. So if you ever get banned, what you can basically tell blizzard is, "I have no knowledge of me breaking the rules, you can check the logs, I logged off at around 12 last night, couldn't have been me." There's no way Blizzard would perma ban you.
Of course there's one flaw in my method and that is the transfer of botted goods to my main account without making it seem like my main account is attached to the botter.