It's the textures plugged into the SSS.  I got his first interjection product, whch I was totally dissatisfied with and returned.  A lot of people actually returned it, especially people with better knowledge on DS's SSS.  I don't have the M4 version but I'm assuming it's the same thing.

What happens here, if I recall, is his settings are too red and the textures blows the mouth and other areas out of proportion and makes them look unnatural.  Honestly don't know why his promos don't show as much as when people use them, he's done something extremely tricky, but looking closely you can still see that "too much" areas (such as the mouth).  I don't recommend the product but wish there were a better product out there.  If you can work in an art program, however, you can tone down that red on the textures, also change the SSS color in DS to not be so red.  You can also work on the diffuse color, turn it a tad blue.  It's best to actually learn these properties then have to buy product to do the work you have no control or knowledge of.

Also ambient is unnatural for character settings.  People don't have "ambient".  Ambient should actually be called "glow", as when you render things with ambients on in dark renders, they glow depending on strength and color, blocking the lights/shadows.  That's not natural and should only be used for glowing effect.  Or simply a cheat thing to make characters brighter in renders (which I never do).

I'll be releasing my new character soon though, with SSS and proper SSS textures, just so you know.

...wolfie