Its more about what was communicated/interpreted than the actual words.

Take for instance: "I'm not going to let some bitch tell me what to do" vs. "Hey bitches, whats up?"

the first statement could communicate that the speaker has issues with females telling him what to do. The second statement is playful and affectionate.

However, because the word bitch is so generic and well used, the first speaker could easily only have issues with unpleasant people, not females. Its not clear.

That's why it is better to talk about a person's pattern of behavior, rather than labeling an isolated incident as sexism.