YOU should have spoken up to the pet owner (that shouldn't read in a sarcastic tone...). Back when I worked in retail, nothing pissed me off more than to see a customer make a giant mess or knock something over and just walk away from it. I knew I couldn't say anything because I'd end up flipping out on them for being so lazy and irresponsible that I'd get fired. But since YOU don't work there, you could have said whatever you wanted to them and maybe they would have actually been responsible for their pet. Just a suggestion...