Your mother and grandmothers and maybe even farther back have been using Vaseline/Petroleum Jelly as a beauty product for years, but like most things used long long ago, our outlook and knowledge has changed. I'm going to go over a few myths and truths about Vaseline you may not know.
Myth - Vaseline moisturizes, and is great for your lips/cuticles/skin.
Vassaline does not contain any moisturizing properties, and cannot be absorbed into the skin. What it does is traps moisture in, preventing any moisture your skin already contains or may absorb internally from escaping. So your skin may feel softer and more moisturized. If you want to use this to your advantage, place a moisturizing cream or product on first, then layer the Vaseline over top. Then the Vaseline will help the product containing water or other moisturizing properties penetrate deeper into your skin, and prevent it from evaporating into the air.
Truth - Vaseline is a great makeup remover
This is true, however you want to make sure you don't leave it on your skin after you use it to break down your makeup. If you leave it on your skin it can clog your pores and create break outs.
Myth - Vaseline helps wounds heal faster
Vaseline creates a air tight seal over your skin, preventing any air to get in/out. This CAN help prevent infection, but it also doesn't allow the skin to breathe. Your skin needs oxygen to rejuvenate, and create new skin cells, so preventing it from doing so can cause more harm than good. You should avoid putting too much on, or constantly having it on your injury. Even on a tattoo, you should let the skin air out.
Things like polyspoin also can create the same negative effects, the only difference with polyspoin is that it contains anti-bacterial properties, and can help kill bacteria.
Truth - Vaseline prevents hair dye from staining your skin
If you place a thin layer of Vaseline around your hair line, nape of your neck and on your ears you can prevent hair colour from staining your skin. We've all been there, with the day after stains, or that rouge drip down the back of your neck. Avoid that easily with this trick.
Myth - Vaseline is a great lubricant
This can be true, but use it in the correct situations only.
You want to avoid vassaline as a sexual lubricant for 2 reasons. One being if you're using condoms is WILL break down the latex. Not it "might" but it WILL break it down. The other being like with the moisturizing myth, your body cannot absorb the petroleum jelly molecules, leaving you with a nasty oily and greasy residue. Yuck.
Using Vaseline to do lubricate body jewelery (eg ear stretching) is fine, if you use a small amount, but ideally you would want to work with a water based lubricant in that situation as well.
Over all this product isn't horrible, but we need to keep the facts straight.
The most basic misguided fact being that people think it hydrates. It alone does not, but in combination with other products it can be very hydrating. Watch your ingredient labels as well, the ingredients are listed from most to least, so if petroleum jelly is before any true moisturizing ingredients or even water, watch out. It may do more harm than good.