If they do not trip, replace them or make sure they are wired properly. Todays codes required GFCI in the kitchen, carorts, garages, unfinished basements, front and back porchs, near the AC unit outside, hottubs, bathrooms. Any code that requires a gfci requires it to be installed correctly. How old is the ones that do not trip, and where are they located?
__________________ "The problem isn't that Hillary Clinton lies. We all know she lies. The problem is that her supporters don't seem to care"