In 2026, standard advice for monitoring brand presence in AI search engines relies on two signals: chatbot responses and server logs of AI crawler visits, both of which are unreliable. The article distinguishes three separate measurements: crawl, citation, and mention. A Semrush analysis by Kevin Indig of 3,981 domain appearances across ChatGPT, Gemini, Google AI Overviews, and Google AI Mode in June 2026 found that roughly 62% were "ghost citations," where the engine used a page as a source but never named the brand. Only 13.2% were both cited and mentioned. Companion research found that 74% of users chose the brand the AI named as their final pick. The engines are inconsistent: Gemini names brands in 83.7% of appearances but links a source only 21.4% of the time, while ChatGPT has an 87% citation rate against a 20.7% mention rate. Across 454 prompt-and-domain pairs, the engines disagreed on whether to name the brand 22% of the time. Indig describes these as "different behavioral systems," and a single blended visibility score destroys needed information. The article notes that server logs are unauthenticated strings that anybody on the internet can type, making them a soft signal.