Tattletales are pretty good. They are usually just trying to ask their parents help. If parents get mad that kids are complaining about other peoples behavior, then the child will not tell their parents when a real problem is going on. This idea will stay throughout the rest of their lives.
Unless you are putting out false or twisted information that could potentially hurt someone who is innocent, then it doesn't matter what others think. Don't be honest just for the sake of being a snitch, be honest because it's right to do so. 10 year olds call each other tattletales, you shouldn't live by the "don't be a snitch" rule if you're a mature adult who's learned the importance of being honest. If you know your best friend is cheating on their boyfriend, you shouldn't be the one to tell their boyfriend, they should. However, if you know someone has convicted a crime, and they happen to be your brother, you are basically holding a criminal. They could rape more people in the future, even if you love your brother, going to prison is what they deserve and need if they're going to change.
Tattletales are a necessary evil required to overcome what the one being snitched to perceives as a greater evil.
A snitch to the criminal is the one who tattletales to the cops but a snitch to the cops is the one who leaks information to the mob, so who really is the tattletale after all?
The tattletale is, by definition, a traitor of trust. This is not good.