The binding on the neck has been clean - Look at the binding on the body! Yuck! Check the buggered up neck!!!
Do ya smoke when playing? Smoking tobacco does wonders for the guitar finish and smell as well! Nothing like a guitar under your chin that smells like an ashtray that sat at dive Las Vegas bar for 50 years. No spittoon? Why not use the sound hole on any old acoustic guitar? Seriously now, do you really want your guitar to have emphysema?
Look here, hope this players teeth aren't this yellow!
This yellow will wipe off with a paper towel and simple cleaner or Naphtha.
The following is a perfect example of a grimy fingerboard
Prevent build up by cleaning the fretboard when changing strings
Maybe its a badge of honor or a way to prevent other people from using your buggered up guitar?
Clean fret boards play faster in my opinion
Dirt, sweat, dead skin, buggers, etc... Clean it or pay $$$$
Most players like the vintage patina of an old instrument but allowing dirt build up is not good for anything. If you are sweaty Eddie, wipe your instrument down before you put it away cowboy. Take pride in your instrument or pay the price.