[Arran]

It might be that they like the taste of the wax coating on many old capacitors, I think it may have been bees wax. As for torn grill cloths, many of the Philco ones tend to have straight patterns woven into them, and between that and the tension of the cloth makes them vulnerable, being 80+ years old and exposed to heat, light, dirt, and moisture likely doesn't help the fibers. I think that many of them were actually made out of rayon, which is produced from cellulose. The chevron cloth really likes to tear, I think more sets have at least one hole in that stuff then ones that don't.
Regards
Arran