We were horrified when we saw an Instagram photo of a woman with painful-looking cystic acne. But not for the reason you might think. Our shock stemmed from the comments.

The image did receive more than 38K likes, and commenters posted kudos for her skin-positive pose. But many others chimed in with scorn and cruelty.

Her experience isn’t isolated. People will often assume information about others based on the appearance of their skin. After all, many believe that the skin is a mirror to your internal health — but that’s not always the case. In fact, without knowing the person — and even when you do — their skin isn’t an open book about their health and lifestyle.

We looked into the most common and hurtful myths surrounding skin issues and debunked them with science-backed info.

If we get a stain on our shirt, we toss it in the wash to remove it. That logic is just one of the reasons why the “poor hygiene” myth is so prolific when it comes to skin conditions. There’s an assumption that we should be able to wash away all spots.

In a recent study on skin misconceptions, survey participants viewed images of common dermatological issues, including acne. More than half of respondents reported the belief that acne was a result of uncleanliness. The marketing of skin care products with “bacteria-fighting” ingredients may also perpetuate the myth.

The truth: Our faces have bacteria on them all the time. And most of us have Propionibacterium acnes, which can cause blemishes but can also have protective qualities, depending on the strain. It can get trapped in pores, however. And research indicates that, for some people, it mixes with their natural skin oils, called sebum, and can create an inflammatory response.

That’s why some folks are more prone to pimples than others. Excess face washing doesn’t help, however, because the bacteria form a biofilm. Instead, too much cleansing can lead to more issues.

The bottom line Acne and other skin conditions aren’t an indication of someone’s hygiene habits.

The fact that some acne stems from bacteria may exacerbate the myth that acne can be transferred from one person to another like an infectious disease.

In the same survey mentioned above, 50 percent of respondents reported thinking that acne was contagious, and nearly the same amount of participants said they’d feel uncomfortable touching someone with blemishes. A similar stigmatizing viewpoint often applies to people with skin conditions that can appear as a rash, such as psoriasis.

The truth: You can’t “catch” acne from touching or being close to someone who has it. Again, we all have bacteria on our faces. An issue that may look like acne can arise, however, if you contract Methicillin-resistant Staphylococcus aureus (MRSA).

But you can contract MRSA from anyone who is a carrier of the bacteria — including yourself — regardless of whether they have acne. Typically, it’s passed through compromised skin, like a cut or sore. Conditions like psoriasis, lupus, rosacea, and eczema also aren’t contagious.

The bottom line People with skin imperfections shouldn’t be feared or ostracized.

The myth about poor hygiene contributes to the myth that people with skin issues are lazy. Other people may have an assumption that someone with acne doesn’t engage in an effective skin care routine, isn’t following one consistently, or isn’t proactive about visiting a dermatologist.

In a 2017 survey of 100 people, more than half said they believed medical treatment of acne would provide an almost immediate resolution. So, the logic goes that if someone doesn’t have clear skin, they aren’t trying hard enough.

The truth: Some available acne treatments target existing blemishes rather than prevent new ones from forming. Plus, they take several weeks or even months to have an effect on current inflammation, and results vary from person to person.

Other skin conditions, like psoriasis, may have some helpful treatments that provide varying results, but ultimately a search for a cure is ongoing.

The bottom line We have no idea, just by looking at someone, what steps they’re taking to treat a skin condition, and really, it’s none of our business. But their skin’s appearance has nothing to do with motivation or work ethic.

Diet has been the scapegoat for acne for decades. A scene in the ’80s movie, “Adventures in Babysitting,” shows character Chris Parker slapping a candy bar out of one her charges’ hands. “No chocolate, your acne!” she says.

Plus, the clean eating movement has connotations that can lead people to think certain foods are dirty or bad, which is untrue.

Just about 40 percent of respondents from the 2016 survey believe a person’s diet is to blame for their blemishes. And processed, sugary, or greasy items are often considered the biggest offenders.

The truth: Researchers have yet to establish a definitive or even casual link between acne and diet, according to a review of existing studies. Some skin conditions like psoriasis and eczema, for example, are actually an autoimmune disease. And although experimenting with adding or eliminating certain foods may lessen inflammation or symptom severity, diet isn’t the cause.

The bottom line Skin isn’t a reflection of what someone had for lunch. Even the most fruit- and veggie-obsessed person can still have acne, redness, or flakes.

One of the most harmful myths of all is that any skin condition is the body’s cry for help.

Several comments on the Instagram post in question referred to the woman needing to heal a severe underlying issue to cure her acne. The concerns surrounded everything from poor diet and lack of self-care to significant disease and even skin cancer.

The truth: Although hormones are often a culprit in adolescent pimples, they aren’t usually a factor in persistent acne during adulthood.

While a condition, such as PCOS, can create a hormonal imbalance that contributes to pimple formation, it doesn’t mean every adult with acne has an underlying condition. Even if someone has an underlying risk factor for acne or another skin condition, only that person should decide whether they’re doing their best for their health.

The bottom line Skin is not a reflection of someone’s medical history or wellness.

To make assumptions about someone’s health or lifestyle based on the condition of their skin perpetuates myths that scientific research often has no conclusive evidence for.

And myths can be hurtful. Consider someone with acne using a caustic cleaner on their face — all because someone accused them of being unclean. Or someone eliminating important nutrients from their diet or even avoiding meals — because someone said certain ingredients were the problem.

When it comes to skin, symptoms and signs may only show part of the picture.

Complexions are rarely flawless every single day. And we should stop expecting them to be perfect — for our own sake and for others. At the very least, let’s stop believing that a skin “imperfection” means the human beneath the surface isn’t doing enough for their health.

Jennifer Chesak is a Nashville-based freelance book editor and writing instructor. She’s also an adventure, fitness, and health writer for several national publications. She earned her Master of Science in journalism from Northwestern’s Medill and is working on her first fiction novel, set in her native state of North Dakota.