I was staying with friends last weekend and they handed me their Santos Martinez SM80 classical guitar to play. The strings were obviously old and yucky. In the low evening light I said that the fretboard was dirty but then the next day I could see that the exposed wood fibres are giving it that rough feel. My goodness, I have never, ever seen such a dried out fretboard as this one.
They wanted my advice as they want to sell it as it was their son's guitar and he has now moved abroad and left the guitar behind. So, I brought it home with me and will return it on my next visit. A good clean all over, polished frets, oiled fretboard and new strings and helped return this guitar to closer to how it should be. The fretboard feels a whole lot better but not perfect.