cast aspersions on (someone or something)
To talk negatively or unflatteringly about someone or something. I'm sorry to cast aspersions on Julie, but her work ethic is really terrible. She hasn't handed one assignment in on time. Bill says that he doesn't want to cast aspersions on anyone, but he still talks badly about us all the time!
cast aspersions on someone
to make a rude and insulting remark. I resent your casting aspersions on my brother and his ability! It is rude to cast aspersions on people in general.