If we are planning a peel of less than the full face, I like to peel areas that are least likely to cause problems if the peeled skin changes color a little due to the peel.  The area around the mouth can be peeled by itself, because that area's skin often has a slightly different color than the rest of the face, as in this woman.

You can't evaluate her skin color after the peel because of the makeup, but in the before picture, it is evident that the skin around her mouth is a little darker than the skin on her cheeks.  If the peel caused the skin around her mouth to be a different color after surgery, big deal: it was different to begin with.