There's no hard and fast rule here, for example...
If you have 3 accounts on the same b.net, all the characters are in the same guild, and your bot account deposits all gold into the guild bank, and then the other accounts withdraw gold from the guild bank, they can still ban you.
Or...
If you trade anything across the accounts, they can still ban you.
Or...
You get a GM that's having a bad day, they can still ban you.
Or...
They just feel like banning you, so they ban you.
Just because some GM somewhere said they won't, it doesn't mean you won't get a different answer from 9 other GM's.