Drax, If you are not the main tank of a group you have No business taunting off the mob if it is attacking the main tank-- that's the point mfbrownbear is trying to make.
If you are not the main tank in a group that means you are a backup or offtank. Therefore if you are taunting off aggro when the mob is attacking the main tank you are doing two things incorrectly:
1) you're stealing aggro purposely from the main tank when you shouldn't be
2) you're wasting your own taunt because if the mob were to attack a caster, as an offtank it's your job to control it. If you are spamming taunt and stealing from the main tank when you shouldn't be, you risk your taunt key being down and not available for use when it's Truly needed.
you also seem to be confused on how taunt works.
I was making a point as to how Taunt DOES work, and if you are maxed out in taunt no matter what lvl you are it will let you have compleate agro from the mobs
it seems like you think that if someone has their taunt maxed it will hold the mobs aggro forever until they die but that's not how it works. As stated before in this thread, taunt works like this:
puts you to the top of the hate list +1 point (this of course only applies to successful taunts, taunt can fail of course)
that's why, if you have 2 people spamming their taunt keys, there will be aggro flopping around, which is something healers dislike usually. Even if the Main tank is at the top of the aggro list, if you taunt the mob successfull it will start attacking you. As a backup/offtank, you should be saving your taunt key for when/if a mob is attacking someone besides the main tank, or if there is an add which needs tanking as well.