I have no idea what's causing this as I've used the dashboard to check to see if I had anything conflicting with anything. When my sim gets naked for showers etc ... his face turns blue (it kind of looks like some sort of face paint blob or something). Does anyone know what's causing this? This only happens with this one sim in particular. Also I wanted to add that the blue face remains even when the sim redresses.

I could be wrong, but isn't that the makeup that shows up after a sim finishes a Pie Eating Contest? Have you tried resetting him?

That does look like face paint. I have all the face paint that came with Seasons set so they can not be assigned at random. If you would like to try that there is a link and some instructions for Kuree's EasyCASP Editor HERE. Once you have that installed you can select the Seasons EP and Hide all the facepaint (or which ever you choose) in CAS and/or untick "Valid For Random" for each of them.

Edit: I should have included the make up that's applied from the Pie Eating Contest that TheRedRavin mentioned .. you can use the same procedure for that in EasyCASP.

Looks like the sim blue himself.

^^Came here to make that exact same joke.

Maybe try checking for faulty CC? Standard question, but any broken facial makeup stuff may be behind it.