Likewise when customers came to visit us at trade shows my boss would sit politely through their compliments, then immediately jump to the question "So what don't you like about our product?"
Fast forward to today. I'm friends with top people at a Really Big Guitar Company and a Huge Amplifier company. Even in private, these C-level execs show nothing but respect for products of their competitors. They are not ashamed to own and even personally use said products (especially vintage ones).
It seems to me that dissing your competitors even privately can make you dangerously blind to the challenges they pose to you, set a bad example for your employees, and also restrict your job prospects should you decide to work for a competitor one day.