If you haven't seen this Gene Roddenberry movie

I highly recommend it

Spectre (1977)
Here is a review
https://filmschoolrejects.com/spectre-1977/

This review does not, however, mention the slashy goodness, which is baarrrly subtext. Everything about this movie is over the top.
While not nearly as outrageously camp, but rather played as a more traditional supernatural detective story, a natural pairing for Spectre would be Baffled (1973), starring Leonard Nimoy, as the American psychic detective trying to solve a murder in England. Here is a review
https://filmschoolrejects.com/baffled-1972/
(and, yes, I have seen this movie about half a dozen times and Nimoy does do the lifted eyebrow thing in it, happy sigh).