When do you decide an employee's conduct needs to be reported to management?

I had a retail job over a decade ago and one of my coworkers always had the absolute worst BO, I doubt he showered or used deodorant at all. One day he smelled so horrid that 5 different customers filed formal written complaints that had to go to corporate.

Then a few weeks later we were all notified at work that corporate was asking all of us in our store to complete a hygiene module course and we all refused because we all knew exactly who the fuck the problem was.