Its interesting because i was reading that applying too many coats of satin or matte leaves the finish 'cloudy'...and people suggested putting gloss under, then finishing with the matte spray at the end.
I suppose it could if it were really thick, but that has not been my experience. I would also say that the amount of coat thickness you will achieve with rattle cans (even 2 or 3) would not be enough to have that effect.

The many coats of clear are to bury the decal (given i can't wet sand like i would normally) but i think i'll create a decal that covers the entire headstock with it being mainly transparent but my logo so i don't have to worry about that problem.
One, I think a decal that large can present it's own set of problems, and two, you can still level sand the matte poly once the decal is buried. Just be very meticulous when you apply the "last coat" so you don't need to touch it after it's sprayed.