How come if someone smiles at or compliments someone of the same gender it's considered being nice, whereas if they do the same to the opposite gender it's viewed as flirtatious?

Nonsense that is not flirty, and if someone thinks that they have a narrow mind.

I can’t seem to tell the difference in flirty and nice. I’ve met plenty of gals that I thought were just being nice to me, only to find out that they were trying to be flirtatious.

If you make your intentions clear in your comment, you will not be misunderstood. Your wording and tone of voice are important here.

If you say to a guy you have seen before, “Your hair looks good today.”, I doubt that will be automatically be taken as a flirtatious ‘come on’.

If you say, “Your look so delicious with your hair like that”, well…. you can expect an entirely different interpretation.

Who says so?

Because we are horny, horny creatures who are generally so insecure that any recognition from the sex we desire is subconciously taken as an invitation to dance the horizontal mambo.

but then, a fraction of a second later, our rational mind kicks in and saves us from ruin.

So much in life is a double standard. However some people are just ignorant. I remember when I was younger being able to play around and be flirtacious and fun with co-workers and they do the same and no one take offense. If someone stepped over the line, someone would say something and shut it down. Now if someone says so much as a compliment, it is sexual harrassment or called and unwanted advance. Dirty jokes can get you fired. Even if its the same sex it can be seen as bad. I had a boss who was gay and I knew a lot of the pretty girls felt uncomfortable around her and would say she hit on them because she would comment on how pretty they looked or she liked their outfit. She would say the same to me at times but we pretty much couldn’t stand each other. I never for one second thought she was hitting on me. Or even when she said it to the other girls, I knew she wasn’t hitting on them either. She would mostly compliment them because they where young and in the in crowd and she felt important to be recognized by them.
It really depends on how things are delivered but some people are too closed minded and just too into themselves.

Agree with @MagicalMystery and I find the double standard irritating as hell. I’m trying to train myself to stop complimenting people altogether. I can’t tell F2F if someone is flirting and my own intentions are usually misunderstood. Best to just stay away from the whole area.

@Randy It’s a total mystery to me also.

Because we live in a heteronormative society that presumes all opposite sex/gender relations are about sex and attraction.

Because you are assuming we are all heterosexual . . .

I disagree with your assumption. Complimenting someone of the opposite sex is not necessarily flirting. Demeanor and chosen words would make that distinction.

@perspicacious Many people can’t make the distinction, even under the conditions you describe.

@stranger_in_a_strange_land We will always have morons around us.

With someone of the opposite gender there is always a chance the compliment was meant to be flirtatious and depending upon the hormone levels the receiver may see more of less than intended.
With someone of your own gender the flirtatious part of the equation is eliminated.
I can say to one of my man friends “Hey, nice boobs!” and we will both laugh. If I said that to one of my female coworkers I’d be fired or arrested for sexual harassment.

A good life rule to remember is: “Don’t be a tease.”

@perspicacious I think @stranger_in_a_strange_land may be referring to people on the autism spectrum who are challenged by scenarios such as described in the question. Folks with Aspergers (a form of autism) can be exceedingly high functioning (read genius) and still be challenged by a subtle scenario such as this. That is hardly a moron.

@Kayak8 Exactly

@Kayak8 When did this become a discussion about autism? The actual question here is somewhat moronic.

@perspicacious It’s relevant to whether or not someone interprets an action as flirting.Most autistic people can’t make the distinction; interpreting statements literally and being unable to read nonverbal cues.

@stranger_in_a_strange_land I did not address autistic people in my answer. I have no idea why you brought it up.

@perspicacious I’ve made my point, whether you understand it or not. (No longer following this question).

I hate this. I visit a local gym that is very small. The town itself only hold about 4 thousand people. So when I work out there aren’t many people there. We all say hello and good morning. (Most of these people are fairly old, in their seventies, etc)
So when I say hello and good morning to young men, I get eyeballed and “checked out”. Its kind of offensive. Its all hormonal, I guess.