I don't know what kind of glue stains they are, maybe from glueing the binding? There are many glue stains on the sides and around the f-holes, too.

I have first hand experience with sanding through plywood (to my defense: It was 60 years old and already worn thiiiin), so I'm hesitant with sanding...

Was able to get the glue spot off the neck with some scraping and a fine blade, but I don't know what to do with the deeper scratches on the front, back and sides. I don't want to sand through, but I also don't want to use filler, as it never looks really good.

Maybe just live with the worn look?