Swearing is against the rules both on the website and in the game itself. It's very hard to moderate though. It's also tough to decide whether to delete a comment just because it contains a swear word, I usually leave them unless it's an angry or negative comment, or that I can easily delete without deleting part of a conversation. If I notice someone swears a lot I usually check their previous comments for more, and often find a ton of negative comments to delete. It's not as common on the website but I sometimes edit it out of posts / hide posts which swear for no reason. We have the rule because a lot of young kids play the game.