-> Exploiting something that adversely effects:
1) In game economy. (to a degree. they didn't action JC shufflers, but they would action someone duping items and selling for profit.)
2) Cutting edge raid progression. (see the LFR exploit)
-> Use of:
1) Bots, 3rd party addons that remove the need for a player to be behind the character.
2) Repeated, highly offensive language (You typically get three warnings.)
When an addon works against the spirit of the game, like the macro above, or during late WLK there was a "Augmented Reality" for raids, that would paint a boss's attacks to make it very obvious if someone was standing where they shouldn't etc. They don't typically hand out bans for it, but instead change the API to prevent and break that functionality. No one was banned for using that AR mod. Now if you modify game files to make ore, herbs, etc stand out (A player in vanilla wow changed all the endgame herbs to WSG flags, making them easier to spot and click.) that CAN get you actioned. I don't know if it's bannable or just a warning, but it is now against the TOS.
They haven't banned people for actual exploitative macros and addons.