The highest-leverage public discussion corpus for ChatGPT AEO, according to Ravish Agrawal at Gamma. Comparison posts and listicles get cited; "we are great" posts do not. Own-community how-tos can rank; comments mostly shift sentiment, not discovery; negative comments can stick in the index for months. Citation lag for ChatGPT is often 30–45 days. Treat as training-data intervention: even when cited, the click usually goes to Reddit, not your site.