The most controversial use of the system is in self-spotting, where a competitive station sends a spot advertising its own operation on the air. Almost all contest sponsors explicitly prohibit this activity in their contest rules, so finding stations that self-spot in a blatant manner is uncommon. Most stations that engage in self-spotting do so by hiding or masquerading their identity as the source of the spot. Because of its easy accessibility and lack of user authentication, identifying such abuse on the packet cluster system is difficult, and may lead to false-positives. Enforcement in cases where self-spotting is suspected can be variable. Peer pressure remains the most effective means of curbing this undesirable behavior.