The Impression You Give May Not Be The One They Get

The "impression" you are giving to those who are on a higher level of awareness, who have functional empathy and abstract reasoning ability, is not at all the same as the "impression" that those with a lower level of awareness, emotional maturity, empathy function, or reasoning ability are getting of you.

You don't look the same to everyone who's meeting you or looking at you, and in many cases, not even close to the same.

And in most cases, even those with clearer perception don't see you exactly as you see yourself. They can't, it's not really possible, even if they are a highly aware and mature individual; they only know a couple of things that they can see, or think they can see. They would need time to get to know you and learn more about you, just like you would need to learn about them.

For those who are less aware and mature, they are looking at you through a stack of thick filters in their own mind.
Bias for or against people who look like you,
prejudice for or against your gender or race,
assumptions and stereotypes about you because of your height, or your weight, your build,
your hair color and the way it's styled,
your clothing,
your accent or speech pattern,
etc. ad infinitum.

It is very possible that they are comparing you to various characters from television, film, music, CARTOONS, politics, history, childhood, etc., and trying to find one that matches your looks (in their mind.)
People do this a lot, but those with mental illness are more likely to believe that your personality is JUST LIKE the character or person they think you resemble. So if you remind them of a girl they couldn't stand in school, you must be "just like that girl". If you remind them of a certain Aunt who was afraid of dogs, YOU must also be afraid of dogs.
If you remind them of a nude-magazine model, well, that can get not so funny very quickly.

The less maturity, reasoning ability, clarity of perception and functional empathy (not sympathy) a person has, the more they are likely to judge others in all kinds of left-field, imagination-based, tales-from-childhood ways, and so are not going to even be able to see you for "who you are".
Further, they are much more likely to believe that they know "all about you" from a few superficial traits, or from hearsay, or from hearing you speak, or seeing your posts online. Or even from your car, your shoes, or your job, or people they saw you speaking with.

However those who DO have higher reasoning ability, empathy function, clarity, and emotional maturity are much more likely to see you closer to who you really are, and to treat you with civility, manners, and respect.

So if someone treats you poorly for "no reason", (nothing you did that was inconsiderate, manipulative, or aggressive...for real...)
it's probably because of their own limited perception and discernment and reasoning ability.

When you find yourself dealing with a person who has some sort of authority over you, or poses a direct threat, and this limitation seems to be the case, it's probably best not to let on that you think they're limited in perception; just keep it as peaceful and calm as you are able so you can figure out how to get away from them as quickly and unscathed as possible.
(Those who have limited perception toward others, with limited maturity, are also more likely to be histrionic, volatile, and reactive.)