Squirrel-proof trash container purchased by the Denver Zoo!
When the zoo staff confronted the company which sold the "Squirrel-proof" containers, the response was, "Well, we were talking about the spring-tension on the lid opening. The squirrels cannot exert enough pressure to open the lid." I suppose that nobody realized that squirrels have teeth sharp enough to crack very hard nuts.
Being a card-carrying member of the Center for Inquiry and a 10-year subscriber of The Skeptical Inquirer, I am naturally skeptical when something is billed as (fill-in-the-blank) proof: spill-proof, burglar-proof, stain-proof, weather-proof, child-proof, escape-proof etc. I also have doubts about "guaranteed permanent" or "absolutely non-staining." Proof to me follows a chain of logical steps toward a conclusion, eliminating false premises, as in the scientific method.
I mostly live in the gray areas. In my opinion, few--if any--things fall into an either-or category. Almost nothing is, under every circumstance, absolutely right or wrong. If I must make a decision, I prefer multiple options. If I must choose between two unpleasant options, I'd like multiple reasons pro and con. When someone professes to have the "only" possible solution to a problem, I omit them from--or cross them off--my list of trusted advisors. (I believe this explains why I'll be voting the way I will in the November election!)