A lot of Whey powders have enhanced levels of Glutamine and BCAA's anyway, so stacking Glutamien and BCAA with whey in such an instance, would be likely to promote poor usage of the additional stacked Glutamine and / or BCAA, because you'd be potentially elevating the levels of such things, beyond the point where the body could cope with what was consumed and then you would create a lot of wasted excess product.
So that has to be taken into account for anyone considering products like Whey powders or BCAA's.
However if you bought a powder with no enhanced levels of such things, then as T.P.W. says, it would be a good thing to do, cost permitting of course
As for things being good for you tasting horrible, I'm getting flashbacks regarding cough medicines.