It just makes you look uneducated, low IQ, low class, unprofessional, like someone who does it because they do not know any better. It says that the person is a follower who copies other people when something is a fad.
I would not say that they are bad. But, often times it makes the person look trashy. Almost like when kids draw on their skin. No offense to any one who has them that is just a reason why they are considered bad.