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None of these answers are really answering the question in the real world.
One I agree with is why it is important to know. In a sense it is important to know. You could argue that you need to know because you are afraid he might come onto you sometime, and you dislike that.
That’s legitimate but it’s a pointless worry because your best friend who you always thought was straight all this time is definitely not gay and he’s probably not even bi. I’ve had hundreds of ostensibly heterosexual male friends over decades, and I never had one secret gay or secret bisexual friend. I never had a friend pretend to be straight but really be gay.
The reason it is pointless to find out in my opinion is because you are going to find out right away anyway. In a number of cases, I got to know men who were gay or bisexual. In most cases, I figured this out immediately because they gave off a very strong vibe of sexual interest the very first time I met. Gay men usually give off a vibe of sexual interest when I am around them, typically when I meet them for the first time.
It’s the same vibe as straight women give off whether they want to date you or not. Non-lesbians give off a vibe that says, “Hi, you are a man. And I am a woman who likes men!” It’s as clear as air, and all or almost all non-lesbians give off this vibe. I mean all the way to women in their 80’s down to teenage girls. It doesn’t mean they want to go out with you necessarily. It’s simply a signal that they are heterosexual.
Gay men typically give off this same vibe. It says, “Hi, you’re a man! And I’m a man who likes men!” It has a sexual overtone in the same way the one the women give off does. It doesn’t necessarily mean he wants to have sex with you, but he might. He’s simply signally his sexual orientation, and in my opinion, humans do this routinely.
I doubt if either is conscious.
However, a problem is that as I got older than 55 years old, I started to meet young gay men who did not give off that obviously sexual vibe towards me. I assume it was because I was no longer attractive to them. So this will work better if you are younger, and it sure helps to be good-looking. A good-looking younger man will almost always elicit this vibe from any gay man. However, once my conversation got friendlier and more intimate with (more than just “here is my order”) that same sexual interest came back, with an odd intrigued aspect to it.
Even if they don’t give off that vibe or you don’t pick it up, obviously effeminate men are often gay. Only 3% of heterosexual men are effeminate, and 67% of gay men are, according to a recent study. The effeminacy is often combined with the sexual vibe, and there is your answer.
If you inadvertently make friends with a gay man, don’t worry. I have done this a number of times. Every single time, as soon as we got alone anywhere, even in public, the gay man came on strongly to me. This is what I meant when I said you will find out soon enough.
Some of your male friends my be bisexual. These are harder to spot, but after a while, he will always give off a sexual vibe around you or make an overt come on. This happened with every bisexual man I have known well enough to become friends with.
Some other ways are a total absence of interest in women.
You start talking women and sex, and he acts disgusted, bored, or disinterested. This is odd behavior as few straight men act that way.
He will never look at women, check them out, or talk about them. None of the gay men I knew ever did that. He might treat women like they are ghosts or furniture – it will be as if they were not even there. This is also very odd behavior for a heterosexual man.
As I said, it’s not something to worry about because in my experience meeting thousands of gay men over my life, they usually make that quite clear after you associate with them closely for a bit.
There are some people who confuse me. A male barista at a coffee shop had me confused for months, as I could not figure out if he was gay or not. I finally decided he was straight because in spite of the passivity, very soft voice, and feminine features, he moved his body in a very rigid, blocky (almost robotic or mechanical), and masculine way that gay men almost never do. Also he never gave off a sexual vibe over months.
Humans are just not good at hiding their sexual orientation.
I might add that once I make a determination that a man is gay, it’s always been correct. It might take me a while to get there, but I haven’t been wrong yet over almost 40 years.
However, I am excellent at reading people almost to the point of being a mind-reader. You have to be very good at reading people to use the techniques above, and many people, typically men, are just not good at that.
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