Count the moles you see. If there are more than 11, you probably have more than 100 moles all over your body. And that means you’re 5 times more likely to develop melanoma – the deadliest form of skin cancer. If that’s the case, get a full body skin check annually by a dermatologist. So why the right arm? Because it’s not the one that hangs out the car window when you drive – so the skin spots are more likely to be moles – and less likely to be freckles from sun exposure.