"She's generous to a fault - if it's her own"

This quote by Bugs Baer is referring to someone who is extremely generous, to the point of being excessive. It suggests that this individual is so generous that they want to give away excessive of their own resources, even if it is not in their benefit. This might be translated as a warning to be mindful when dealing with someone who is overly generous, as they might be willing to distribute excessive of their own resources without thinking about the repercussions. It could likewise be interpreted as a compliment, as it implies that the person is so generous that they want to distribute excessive of their own resources. In either case, it is a pointer to be conscious of how generous somebody is, and to be knowledgeable about the possible repercussions of being extremely generous.