Right, to echo others, in my experience its better to have a clearly marked "XXX Brand shampoo 3oz" bottle than a clear plastic travel bottle filled with shampoo. It dosent' matter what brand of shampoo is in the bottle but if you make it easier on the TSA agent (ie shampoo in here, 3 oz, clearly marked) it will be easier on you.
So, IMHO to save yourself potential hassle, go to the CVS or Wallmart and get the cheapest shampoo, conditioner, mouthwash travel size you can find, empty it, rinse it and then fill it with your preferred brand. Put it all in a quart size ziplock and then don't forget it has to go in a bin separately (as my mil did).
TJ