I had a hard time healing my belly button the second time I got it pierced, which is why I've been very reluctant to go and finish off the third one. Like, got the second one 4 or so years ago and haven't gone to get the third. (I have two next to each other)

My eyebrow also never really healed. I think part of it was that I had a bar that was a little bit too short in it, but the next biggest bar ended up with a bunch of space on either end hanging out of my eyebrow and I thought it looked kinda stupid. So I took it out a year ago and you can hardly tell it was there most of the time.

My surface piercings were the shortest lived. I had a surface bar between my boobs for just over a year, and I had two bars in my stomach area as sort of really high hip piercings and those lasted about 8 months. There are scars from all of them, but over time they've become much less noticeable. I knew going into all of them that they'd likely reject, and I was right. The only good options for a permanent piercing like that is to get a microdermal which is like a little implant, and that's a little too permanent for me right now. In the future I'll probably get my sternum decorations back.

I don't regret any of my piercings, and my warnings of "make sure you do your research" still stand. I did a lot of research before getting my tongue pierced and the only issue that I have is plaque on the bottom ball because I don't take the time to remove the bar and clean everything that way on a consistent basis. No chipped or cracked teeth, no gum loss, no root canals. My dentist never even gave me a hard time for it. Lip rings are another big cause of gum loss. I know mine has eroded my gums a little bit, but nowhere near as bad as it would have if I wore a stud all the time. Some people can wear studs with minimal problems. But do a lot of research because piercings that go wrong can fuck you up in the long run.

I had my tongue pierced; I cracked three teeth in my sleep and swallowed one of the ends of the barbell when it came loose. I'm still trying to get it all fixed almost six years later.

I have my ears done. The woman who did one of my cartilage piercings didn't have a very steady hand and twisted the needle going in, so the piercing itself has a curve and I have to twist the earrings as I put them in... Also, having the entire ear (7 piercings in one ear) done makes it gad-awful to clean them, they have to all be taken out and all put back in and it takes forever.

Another grand secret of the universe, never get the cartilage on both sides done on the same day... You will learn to sleep in new and interesting positions to avoid all pressure on them.

And a messed up piercing like the cartilage one I described never stops aching as long as there's a ring in it because the ring applies pressure on the cartilage where the piercing curved.

My left nipple piercing rejected three times. It never fully healed and permanently changed the shape of my nipple.
I've gotten keloids on cartilage, but if you know how, you can make those go away.
I had my sternum pierced, twice, the second time it was the most advance surface piercing technique around, and it still rejected. Big scars from that puppy, but they mostly just look like chickenpox scars now. Never had issues with any of my oral piercings; if you get them far enough back and use really short bars, there is very little risk for chipping teeth.

Lip piercings erode the gums and teeth and do a lot of damage if worn for years.

Everything can get infected, I think belly buttons have a high rate because they are so, so popular and people blow off the instructions they are given. They also can reject, just like any piercing.

Eyebrows can leave nasty scars, because they are a surface piercing but rarely treated like it, as they reject or grow out slowly, they leave long, scars. I only suggest eyebrow rings as a temporary thing.

I pierced the top cartilage part of my ear about 5 times. They never would heal and would always get infected and I'd have to take it out and heal and then try again. You would think after the 3rd time I would have given it up, but no I just kept trying. It's all healed now, but I have a tiny lump of scar tissue on the back of my ear from trying so many times.

My biggest issue has been with scar tissue on my nipples. I had the left one done and the right one had to get done twice (first time was crooked). I'd suggest not getting piercings in the summer if you're sweating a lot. It can really sting!

I've had my navel done twice. The first time the bar was too short. The second time the bar was notched from when someone bent it for me. Note: Fat guys shouldn't get belly button piercings. I'm counting myself in on that.

My eyebrow got infected but that was my fault because I had to switch from metal to plastic in a week. Took forever to get the infection to clear up.

I had my cartilage on my ears done and it didn't get infected but it hurt almost constantly. I think that area was just too sensitive on me to have anything done. I ended up taking them out.

I had a friend that had her nipples pierced and got in a car wreck that ripped them out. After that, I will never get mine done. Scarred me for life.

My husband has his tongue pierced and it developed some sort of bizarre growth around it. It now has to be surgically removed.

My nipple piercings were rejected, leaving me with scars and reduced sensation.

I'm a good healer, so I've not really had any problems other than minor short-term irritations.

My nose piercing was never totally happy because it had to go in and out a lot for work.

I don't wear earrings all the time, so if I haven't for a while & then I put them in, they'll get a wee bit sore for a day or two.

My most annoying piercing problem was actually the result of healing too fast. When my first tongue piercing was about a month old it got irritated from spicy food. So I took it out when I got home to clean everything & rinse my mouth out & such. Ended up falling asleep & the hole was basically gone by morning. Grr!