RevisionDojo, a YC-backed test prep company, has been accused of astroturfing and other unethical marketing practices on Reddit, including creating fake accounts to promote their services and downvoting critical comments. The company has allegedly been paying high school students to write promotional posts and has been soliciting copyrighted materials from students. These practices have been documented by users on the r/IBO subreddit and have sparked an investigation by the moderators. The company's tactics have also been used on other platforms, including Trustpilot.