Google reviews schema guidelines to prohibit vulgar or profane language
Make sure your reviews don't contain profane or vulgar language. If they do, Google can remove your review rich snippets.
The new guidelines section added a line that reads, “[P]rofanity and vulgar language are prohibited. Do not include reviews that contain vulgar or profane language.”
This means that if you mark up your reviews with schema for Google and some of the reviews contain profanity and vulgar language, you need to remove those reviews from your website or remove the schema.
Since reviews are left by your users, it can mean that you need to make sure to adapt your internal quality controls to ensure old and new reviews do not contain such language.
If you do allow profanity and vulgar language in your reviews, Google reserves the right to remove your rich snippets from the search results.
This was first spotted by Aaron Bradley.