While many pups go crazy at the sight of these green treats, others have never even gotten a minty whiff — but why is it that the toothbrush-shaped Greenies have so many critics? The dental snack has chewy curves to fit around a pup's chompers to significantly control plaque and tartar build-up. . . . yet many pets then have trouble digesting them, opting to bite off hard bits and just swallow them whole. In addition to complaints of runny poo, the treats have come under fire in the past, with stories of veterinarians having to perform surgeries to remove undigested chunks of Greenies from the esophagus and other parts of the digestive tract. I still have pet-owning pals who own up to feeding their pets these popular treats, while others now shy away. How about you?