Whether it's sporting a short haircut and a tom-boy wardrobe, or short-shorts and eye liner, there are some controversial attributes one can have that sways assumptions away from the norm. In this day and age, that can be helpful in some ways, but in most situations, it can be really annoying and sometimes dangerous.
You never really get the chance to come out when you "look gay". This can be helpful when meeting new people or possible significant others, avoiding the shock factor followed by statements like, "I never would've guessed!" "Have you always been?!" "When did you know?" ....dude, do we really need to talk about this just because I don't portray myself a certain way? My appearance didn't invite this line of questioning and honestly, it gets old.
The downside to people assuming is once they decide, it's written in stone. You don't really get the choice of explaining that you might not just swing that way. For people that are pansexual, bisexual, asexual, or another variation of queer, this can be extremely frustrating. The public eye might accept that one side of you, but there's way more to you than can be shown.
Even when you do explain it, though, sometimes people forget or even go as far as not believe you. For example, if you're female and have been dating a female for a long time, people tend to assume that you're both strictly lesbians. However, one of you could be pansexual and the other one bisexual, or neither of you could identify as gay at all and just happen to like each other, and so on.
Then there's the other side of this: Looking gay but not actually being gay. For guys, this could mean dressing feminine, caring a little bit more about their appearance than other guys, being interested in non-stereotypically masculine things, etc. For girls, it could mean being sporty, dressing unisex, not wearing makeup, etc. This poses a problem because it's almost like people are waiting for you to come out of this non-existent closet when you're just doing your thing. It can get frustrating when trying to find a partner, and just in daily life, attempting to defend your sexuality and people laughing, saying, "Okay, sure."
However, if you do happen to look like your queer sexuality, it can pose more problems than just being questioned about it. You might get misgendered a lot (public bathrooms are actually hell on earth), to the point where it's better to let people assume than to embarrass them. However, the biggest thing is probably the dangers that accompany.
By appearing proud of who you are, no matter what it is that you're proud of, there comes hate. It used to be much worse, but that doesn't mean it doesn't exist anymore. As the world saw a few months ago in the Florida Nightclub Massacre, being gay isn't always safe, and showing people before you even get a word out can sometimes draw the line between safety and serious threat. This can be terrifying, whether you're a drag queen just trying to walk home after a show, or a tomboy just holding hands with your lady, you can still feel it. The double takes, the whispers, the disapproving looks - they're still very real and disheartening and almost everyone has an experience of it.
However, at the end of the day, no one should stop you from being who you are. If there's anything to learn from the past, it's be unashamed and walk tall because there's absolutely nothing wrong with who you are.
Giving in to social norms won't make progress. It takes a long time to learn in some cases, and in this time, one can develop a lot of insecurities and mental health problems. However, to realize that being who you are is more than okay - it's AMAZING - is like unlocking the best secret known to man.
People who do challenge those social norms don't always get there without support, though. So if you're know someone who gets questions like, "Are you a boy or a girl?" "Are you SURE you're straight?" or "Is bisexuality ACTUALLY a thing, though?", be the person to step up and defend them, even if they're a stranger. It'll mean more to them than you'll ever know.
Similarly, if you're about to question someone's sexuality based on their looks, think twice before doing so. You really have no idea how often if happens, if they're still questioning, or what's going on with them. Sexuality isn't something that can be expressed by physical stereotypes - it can only be expressed by the one thing the world needs more of: love.