There is a filter, yes. of course, filters don't catch everything, and filters are also disabled in /msg, and thats why reports exist.
~ @Muunkee
Thank you for telling me about the /msg, I forgot about the private messages in a project I was working on.
I made a chat filter for bukkit 1.10.2 called MinecraftChatFilter, and it filters through private messages, along with other stuff(books, anvil, signs, usernames, and the chat)
You can find it here:
MinecraftChatFilter - Bukkitif you ever want to use it. Obviously, this will never be able to replace a full staff team, but I hope it helps manage the chat.