Terry, this is really two questions: (1) the acumen of publishers and (2)
these particular books.
About the acumen of publishers I can cite only my own experience. In 1978,
the year of the suddenly statemental T-shirt, I was a painter. "This is
street literature," I thought, & after fighting the urge for at least a
week, learned photography to record the people on the street in their
statements. I took an album of ur T-shirt photos ("Save the Whales," "My
Parents Went to Florida...." plus a few custom obscenities) to Crown
Publishers, which considered it at length, ultimately rejected it on
advice of sales manager who said, "we couldn't get the book into the
stores before Christmas [1979] and by then the T-shirt fad will be over."
As for the books you mention, I have probably spoken strongly enough
about the Scopick to incite a law suit and will add only that people have
told me, when I corrected them on a gum "fact," that I must be wrong
because they'd read it in Scopick.
The Gum Oil book is widely listed, and so presumably widely bought, but I
doubt that people read it. I have not heard of any successful work in the
process, nor come across mention of the book except once on this list
(generally disparaging) and in the venues of its sale. The author's work
illustrating magazine articles on the process is conceptually south of
Hallmark Cards and multi-klutzy..
However, I would think that a person with a serious interest in hand coated
paper would want every book s/he could lay hands on -- but what do I
know, I voted for Adlai Stevenson.
Judy