You can’t control everything. There’s always going to be the person who puts peanut butter in your casserole, tries to break the rules of your game or use your art as a cocktail coaster. Sometimes they they want to push the limits and sometimes they're just doing what makes sense to them. They can still help you make your things better.
You want to do user testing with folks who put your work through normal paces. They’ll help you you understand how your product suits normal people’s needs. But you also want people who will stress test your concept. Challenge users to break your design. They’ll surprise you by helping you make your product more stable and they may even come up with new ways to use what you’ve made.
Adults have a tendency to withhold opinions because they don't want to upset anyone. Inviting them to do something unexpected might help them remove their filter and get down to having some fun.