How can I get my grandmother to see that her dog does do bad?

My grandmother lives with me my mom and my sister. We have 3 small dogs Cutie Silky and Dexter. My grandmother favors Cutie over my other dogs. She really does. Like if one of my dog chews up a toy and gets it every where it's horrible, but if it's Cutie it okay. And Cutie gets away from everything. She even poos inside the house. When i try to correct her grandma comes and says dont do that to me. How can I get her to see that without being mean to her? Believe me I've tried to tell her but she never listens