Over at Orange Crate Art, Michael Leddy quotes this terrific advice from graphic designer Milton Glaser on avoiding toxic people:
There is a test to determine whether someone is toxic or nourishing in your relationship with them. Here is the test: You have spent some time with this person, either you have a drink or go for dinner or you go to a ball game. It doesn't matter very much but at the end of that time you observe whether you are more energised or less energised. Whether you are tired or whether you are exhilarated. If you are more tired then you have been poisoned. If you have more energy you have been nourished.