Bert, as soon as I saw the guitar I thought "Folk Art." As far as folk art goes I am a rank amateur, but I've seen a lot and am willing to make a few generalizations off the top of my head based upon what I've seen. The following isn't intended to be a definition of "folk art" that a scholar would take seriously. It just shows where I was coming from. To me the guitar is folk art because it embodies the following principals:

More is more - More is better. Notice how "busy" the guitar is.

No emptiness - The creator of the guitar decided to leave no space untouched. Not necessarily a fear of empty space. It simply never occured to him that the empty space can be as important if not more important than the "stuff."

No "rewrites" - One of the hardest decisions an artist must make is to sacrifice a beloved part for the good of the whole work. Imagine a director who decides to omit his favorite scene from the final cut or a writer who deletes a favorite paragraph from a final draft. I can't read the mind of the guitar's creator, but the guitar looks more like a sketchbook than a complete work.

The devil is in the details - The guitar shows an obsessive attention to the perfection of the details rather than a consider of the artistic object as a whole. It looks to me like it never occurred to the guitar's creator to step back both literally and figuratively from the instrument to view it as a whole.

The medium is the message 1 - I don't see any consideration of the "appropriateness" of the medium for the creative activity. It probably never occurred to the creator to ask if a wooden guitar were the best recipient of his artistic activities.

The medium is the message 2 - I see no appreciation and use of the unique characteristics of the medium. A guitar is a very interesting object in and of itself. Lots of different colors, textures, surfaces, etc. for the artist to play with. All that the guitar's creator has done is treat it as a bunch of surfaces to carve and paint on. You get the impression he's fighting the guitar rather than working with it and its strengths and limitations.

Just my $.02