Why adding a list of banned words improved our AI email drafts away

When we first started using generative models to create outgoing sales emails every message sounded too formal and not natural. When we wanted a casual style the results were full of stiff company phrases that prospects quickly ignored.

Telling the model to "write like a human" usually doesn't change the words it uses most. Instead I looked at fifty of our AI emails took out the twenty most repeated adjectives and verbs and put them in a strict no-go rule at the end of the prompt.

Taking those words out made the model use simpler and clearer sentences. Our response rate for emails went from 2% to almost 7% in just two weeks after using the new prompt and our sales people spent half the time fixing the drafts.

If your AI writing sounds the same, as everyone stop adding style adjectives and start banning the specific words you don't want. What words or phrases have you decided never to use in your content prompts?