These sorts of comments about 'non-professional' piercers annoy me a bit. I am in Australia so under totally different regulations, but we were fully trained and licensed and the premises was accredited with regular spot checks done. We had strict rules about having a separate room for piercing, the way it was cleaned, the way our materials were stored, etc. These are the same rules that apply to tattoo parlours here. My workplace received a 100% score and 5 star rating every year I was there. We even pierced the head of our local council's health department's daughter (which we awkwardly found out just before the piercing when she looked up at our certificate of accreditation and proclaimed 'that's daddy's name!'). Admittedly though, I have seen a couple of
YouTube videos of girls having their ears pierced at mall places in the US that definitely wouldn't have passed our accreditation and with piercers whose technique left a lot to be desired, so it could absolutely be different over there!
We also used a new type of gun that is totally sanitary - the piercing is done with an earring pre-loaded in a sterilised cartridge. The cartridge just clicks into the top of the gun and when you squeeze the gun the cartridge pushes the front of the earring onto the back. The gun never touches the ear or the earring (theoretically you could pierce with just the cartridge, the gun just makes your hand steadier) and the piercer doesn't touch the earring through the whole process, unlike the old guns where you had to remove the earring from the packaging and load them into the gun then put the back on by hand. These guns also don't make the awful loud bang that the old ones do! Even with the needles the piercer still has to remove the earring from the packaging, put the back on, etc. These new guns mean the item doing the penetration and the earring (here, they are the same thing) have absolutely minimal exposure to outside elements - mere seconds of being in the air. Plus, they are still cleaned before and after each piercing. They are as close to 100% sanitary as you're going to get with piercing.