Again, if you're altering the taste, you're not garnishing it, you're seasoning it. The moment you use something to change taste(and pepper, when cooked on a stick with meat will ALWAYS change taste) it is no longer a garnish, it's a seasoning agent.

I agree, garnishing a dish makes the visual appeal wonderful. They say you need to be able to eat a dish with your eyes, as well as your mouth, to fully enjoy it. But when you're changing the taste, that's not garnish and should be added into the ingredient list, or ex'ed out of something that has to be cooked together, as again, a kabob is cooked together, and it's on a stick, nothing more.