Leaving the neck wood bare can be a problem. Changes in humidity will alter the shape (although they do feel great). This neck could become bowed in or out, or even worse, twisted.
Should use a neck oil on it per manufacturers directions (like the Peavey EVH Wolfgangs), or better yet, go with a thin coat of clear poly varnish. Same for the body (could use clear laquer there).
If string buzz gets introduced as you move up thru the higher frets, and eventually the notes don't even appear, the neck is probably bowed and/or twisted. (also make sure the strings are not contacting the neck pickup or mounting ring). Here's a few easy ways to check the neck:
1. LIGHTLY fret the low E on the first or second fret and with your right hand, lightly fret it on 20. If there is a gap between the E string and any of the middle frets (5-18), the neck is bowed outward (the most common neck flaw). Careful-Fretting too hard will create a gap. If there is not a gap, lift the finger on #20 and see how far up you have to lift it before the string lifts off the middle frets. If it is more than a 1/32" or so, the neck is bowed inward. Either case requires a truss rod adjustment. Bowed inward - Loosen the rod 1/4 turn. Bowed out - tighten 1/4 turn. Give it a day or so to settle in, then recheck. NOTE-Depending on the truss rod - the adjustment could be the exact opposite. There are some odd ones out there.
2. Straight edge - My preferred method. Get a metal straight edge of some sort like a carpenters framing square or some 1"x1/8" flat iron from the hardware store. Make sure the edge is long enough to reach from #1 fret to top fret. With the guitar up on a table, strings off, lay the straight edge on the neck (not flat, on its edge) like where the E string would be, starting at fret one (not on the nut). Each fret should contact the edge. Gap=bowed out, if it rocks on the middle frets (gap at #1 and #22), its bowed in. If some frets are higher than others, you need to have the fret leveled and re-crowned. Slide the edge to position where each string would be. Make notes of the frets that change, more gap less gap, etc. Changing gaps means a fret level is in order.
3. Twist - An easy visual check. Holding the guitar out in front of you, neck pointed away, pretend your eyes are a string, looking down the neck from the bridge to the nut. Really get down close to the body. You should be able to tilt the neck up and down and see the level of the frets. As you tilt the neck up, each fret should appear (completely) like they are stacked on top of each other. If either of the edges (left-low E, right-high E) of the lower frets do not show completely, the neck is twisted. Same for the upper frets. Neck twist is a bear to deal with and if severe, usually means trashing it. Usually, the frets would need to be removed and the fretboard re-leveled.
I once thought a "Sweeping Arpeggio" was an Italian janitor.
