What is a society where you can secretly snitch on your neighbor like?

Throughout history, there have been societies where the power structure seeks to control the society by encouraging citizens to snitch on each other. The Soviet Union comes to mind. Iran under its current government is also a good example.

In such societies, people are encouraged to report others for violations, but they never have to stand behind these accusations. They just have to make them and the secret police decide what to do about it.

Additionally, citizens who might want to curry favor with those in power (or indeed, with the entire “right thinking” population) might publish statements in which they cast out various slanders about some unnamed group of people.

What is it like to live under such a regime? What does it feel like? How does it affect your actions? What does it do to you when you know that any of your neighbors might be ratting you out, or even throwing some baseless accusation at you? What is it like when you have no idea who the secret police are because they wear masks whenever they show up at your house? What is it like when no one has to be responsible for their actions to slander or hurt someone else?