when you don't have the necessary skill or experience, you will be the one who makes a perfect complexion look plastic
we must bare in mind that when we produce a photo (especially one of a high profile model) for client, they may not necessary be using it only for viewing on monitors. They will be using it for an assortment of media from magazines to poster to wall mural.
And every little flaw from wrinkles to stray hair will be amplified when the media is large.
Till date, I have yet see a model with flawless complexion and a MU artist whose skill is so superb to produce those ads you so frequently see on magazines.
So like I mentioned earlier, it will depends on what purpose the portrait is for. If it's for photo sharing and posting in forums, by all means do it with minimal touchup. But if it is for commercial, you can't stop there and tell your client it will look plastic. You are being paid to make them looked flawless and yet without having a plastic look.