Here are the guidelines that company communicators can pass on to those leading the negotiations with celebrities and entertainers:
You'll have more legitimacy pursuing a moral escape clause if you "associate it with the value of the company."
Try to incorporate language that shows that you have a right to terminate the agreement if the spokesperon acts in a way that's damaging to your company.
Make sure your longterm plans gel with the image surrounding the event or product and consider the possible fallout.
It's okay to conduct a background investigation but make that clear up front.
You'll have additional leveraging power if you couch the morals clause as being part of the interest of protecting the company's intellectual property - specifically trademark.
Make sure that both parties agree on the drawn-up contract, not just the "rough sketches of the deal."