The original post is on her lj (http://vynehorn.livejournal.com/14488.html); with her permission I'm cross-posting it here because I suspect some members of this community will know more than we do.
Why don’t shoemakers get any respect? I heard this outlandish insult at the tool sharpening class I attended this past weekend. I had brought a curved awl to the class because I wasn’t sure how to sharpen it. It was cool because I stumped the teacher, who was a walking encyclopedia on woodworking tools. After showing me the right way to sharpen it, he mentioned that carpenters and woodworkers use this phrase to indicate poor workmanship. I had never heard of this insult, but another man in the class, whose father had been a cabinetmaker, was also familiar with it.
Eloise and I puzzled over the origin of this bizarre and obviously inaccurate put-down. The only explanation we could come up with was that it actually refers to cobblers, who repair (rather than make) shoes and who are basically doing patch jobs. It’s denigrating to cobblers too, but it makes slightly more sense.