What I couldn't remember wondering about on first viewing was the degree to which the audience is meant to recognize the villain of the piece, Bruno - the stranger who proposes exchange murders, and then carries one out, leaving tennis playing Guy in a bit of a pickle - is homosexual. Certainly, on viewing it now, the hints seems everywhere - but is that just because I have read somewhere in the years since I saw it that this was indeed deliberate?
Realising that it was based on a Patricia Highsmith novel, and knowing that gay elements appear in her other stories, I would have thought that the homosexual side would have been clear in that source material. Yet according to Wikipedia, the movie screenplay made more of out of a homoerotic element that was only "hinted at" in the novel.
Now that we have gay studies as part of academia, there's lots of "queer" movie analysis on the net about the movie, together with Rope, the other Hitchcock film with a clear homosexual subtext. (With Rope, it's hardly in dispute, given it was a fictionalised version of the real life Leopold and Loeb murder - and they did have a sexual relationship.) You can Google for "Queer studies Hitchcock" if you are inclined.
Anyway, what I didn't realise about all of this was that the actor who appeared in both films, Farley Granger (who played Guy in Strangers, the definitely heterosexual character) was clearly bisexual in real life. His Wikipedia entry contains an awful lot of information about his sex and relationship life, much of it surprising, presumably sourced in many respects from a memoir he published in 2007.
He was, it would seem, someone who it would be difficult to categorise as other than genuinely bisexual, right from the start:
It was during his naval stint in Honolulu that Granger had his first sexual experiences, one with a hostess at a private club and the other with a Navy officer visiting the same venue, both on the same night. He was startled to discover he was attracted to both men and women equally, and in his memoir he observed, "I finally came to the conclusion that for me, everything I had done that night was as natural and as good as it felt ... I never have felt the need to belong to any exclusive, self-defining, or special group ... I was never ashamed, and I never felt the need to explain or apologize for my relationships to anyone .... I have loved men. I have loved women."You can then read in the rest of the Wikipedia entry about the enormously lengthy list of flings and relationships he subsequently had with both men and women had throughout his long career of (mostly) pretty B grade movies and TV.
Incidentally, Robert Walker, who played Bruno, seems to have been definitely heterosexual - or, at least, I would presume so seeing he had been twice divorced by age 30, and had children. He suffered serious mental health issues, and died of a combination of alcohol and an injection his psychiatrist gave him (!) at the age of 32. (He could easily pass for older in Strangers, I reckon.)
I haven't read whether Hitchcock knew of Granger's sexual inclinations before using him in two movies with a gay subtext. (Apparently, Granger even slept with the gay screenwriter for Rope, but whether Hitchcock ever found out, I don't know.) But it is a little odd how Hitchcock also liked using Cary Grant, who, despite a string of marriages, was widely rumoured to have been in at least one homosexual relationship when he was younger.
Anyway, old Hollywood certainly carried its fair share of gossipy intrigue. And the degree to which Hitchcock didn't mind using homosexual subtexts as a signal that the characters were prepared to do anything, within or outside the bounds of society's mores, is somewhat interesting.