The terminology of fetish, of course, does throw one back to the older use of the term, which implies an object in which something sacred or supernatural resides, or perhaps which can be used to call up some sacred or supernatural part of oneself. But that's by the way.
There was one throwaway remark in the article that caught my attention:
The existential approach to mental disorders developed in the 1940s and influenced a view that fetishes had complex personal meanings beyond the general categories of psychoanalytical treatment. For instance, the Austrian neurologist and logotherapist Viktor Frankl once noted the case of a man with a sexual fetish involving, simultaneously, both frogs and glue.
Hmm... Well, real life can throw up situations wilder than any author might imagine, I guess. I'm not sure if I'd ever want to write a story that included such a fetish, though on past form even saying that is likely to mean some situation arises in which it becomes important that I do. I feel I want to know more, but also that I might not like what I find...
For the truly interested (or the truly perverse) the case is briefly mentioned in Frankl's book On the Theory and Therapy of Mental Disorders (2004) - in footnote 9 on page xxiii, which refers you another footnote and that in turn to an audiotape of one of his lectures. I guess I might not get to find out more details anytime soon... unless anyone out there would care to enlighten me?