The most reliable heuristic humans use to detect AI isn't necessarily structural—it's vocabulary. We get a 'spidey sense' when we see certain words clustered together. I've spent the last few months tuning the generation engine for my text SaaS, and the single most effective way to make the output read as human isn't a complex prompt chain; it's a hard banlist. Forcing the model to never use words like 'Unlock', 'Delve', 'Supercharge', or 'In today's world' instantly changes the tone. Humans aren't really detecting AI; we're detecting RLHF-optimized lazy writing.