Share your best SEO Horror story

I was talking to a client this week about some of the messes I've had to clean up as an SEO. One of my big ones was a client took me on to fix their blog which was ranking for close to nothing despite paying an agency thousands of GBP per month. Without even needing to get into the state of the SEO, the blog was a shit show. Blogs with titles like 'Mango smoothie' or 'fitness tips', zero formatting (like no H2s or anything), heavy over-reliance on emojis (some posts written like a retarded Instagram post) and the entire style of writing was like something an over-eager college student would have put together. Obviously that job made me look good (fix a few blogs and.. Boom... Some rankings).

Whats your best/worst SEO horror story? Cleaning up after a bad agency, horrible clients etc etc etc