Your second sentence answers your question - you're striving for a realistic look. Therefore whatever it takes to get that realism. And once you've done faces, you'll move onto something else. Photography is not simply about copying what is there, what the eye can see, but capturing the beauty of what is there. Whether its adding a face or adding a warm tint, if it makes a good picture better, so be it. Put another way, if your picture was spoiled by a pink blob of a face, why wouldn't you change it?