A famous case study when it comes to crisis PR, Pepsi was involved in a strange backlash where a syringe was allegedly found in a drink in Washington.
The following week there were over 50 reports of Diet Pepsi tampering, which all turned out to be a hoax.
Negative press is not ideal - no matter what the truth is. Pepsi managed to work with the FDA, which was satisfied that the story was fabricated, staunchly denying any accusations.