Skin has every color in the rainbow in it. The colors are subtle, but they're all there. So, using different filters will produce different results. It's also common for some photographers working in B&W to use colored gels in their lights to help control the tonality, as opposed to using an over-the-lens filter. This allows you to apply different "filters" to different areas. It also gives you a better idea of what you're end result will be.
One thing that has traditionally been overlooked in portraiture is how different colors of skin can look vastly different under different conditions. Most of what you'll find online and in print about skin tones and photography applies mainly to traditionally north-western European skin tones. Much of what is written doesn't apply to people with other ancestries or skin tones. For instance, darker African skin tones tend to hide all kinds of wonderful overtones and undertones of color that most photographers will overlook assuming what their seeing is just a shade of brown. When in reality, there can be strong shades of purple, yellow, green, blue, or anything else that can really pop under the right light.
