I've seen more than a few times a single word change A/B sales 1%/10000% of a category. Sure that means more the bigger you are, but you would be surprised how often words turn people on or off. They get confused

Anyone who has spent time doing ad copy levels of wordsmithing would probably understand. Imagine Nike's creative dept saying Nike--Just do stuff. Words matter. Would the Squatty Potty sell as well if it were the Pooper Stooper?

Edit: most often the offending word was a turn off or confusing to people in a way that only became understood after the fact. Oh! That's why. The right word usually removed barriers for client understanding. Sorry I can't remember specifics atm.