Let's be clear about one thing: It's very obvious to dermatologists when someone has been a little too hands-on with a skin issue.

"Please don't do surgery on yourself in your bathroom," says Krant. Your bathroom, says Krant, is where little pimples become scars, sun damage becomes infected skin, and mild skin fungus turns into tinea incognito, a deep and spreading mess.

Perhaps the worst outcome of self-inflicted surgery is when people cut off their own skin tags and moles, says Jaliman. "The results are terrible, and leave a lot of scarring." Plus, even if you do manage to cut off the growth (a difficult feat, since cancer cells can wrap around surrounding nerves), those cells need to be looked at under a microscope in a lab, says Engelman. Under the scrutiny of a professional, cancer cells can often be traced to their origin in the body -- meaning a doctor can tell you if you have cancer elsewhere that needs to be addressed immediately.