Excellent post. I’ve played with weaving strips of paper and other materials, strips of aluminum foil, and even guitar string ends through the strings of a normal steel-string acoustic guitar. That can create some interesting buzzing sounds.
I was also going to suggest the old trick of recording a track, then using a microphone to capture its playback and layering those takes. Do that several times and It builds up phase distortions and room resonances which can be interesting. There’s the plug-in that adds crackle and noise as well. The 30-band Graphic EQ has the old telephone setting. There’s so much one can do to utterly ruin a good steel-string’s sound. 
Obviously this is for a scratchy, muted, buzzing kind of sound, not a soulful, clean dobro sound.