It's amusing, and a mild peeve, to see boats advertised with bad pictures and poor staging.
Another minor peeve is when owners represent normal maintenance as upgrades. Wow, a new impeller and a new belt on the engine!
My major peeve is when a boat's condition is misrepresented. The boats I've traveled over three hours to see that turned out to be crap are hard to forget. No amount of questioning on the phone or email is effective when a broker or private seller will lie to get you to drive out of state to view their smelly, poorly maintained "excellent" boat.
A local ad for a 1986, 36 foot Catalina in "like new" condition annoyed me enough to contact the owner, even though I was not boat shopping. We can argue all day long about what "fair", "good", or "excellent" mean, but "like new" has only one meaning. The owner's photos revealed a 1986 boat with all the wear and tear one might expect on a boat of that vintage with average maintenance. I emailed him, listed the obvious defects, and asked him if Catalinas were really leaving the factory with those defects in 1986, and suggested he drop the "like new" description. Seller was unreceptive to my suggestion, and maintained that his boat was truly like new, and became abusive about it. I countered by explaining to him that I've sailed past his boat in the mooring field when no one was around, and maybe he should modify his listing so as not to piss me off. And, he did LOL.