Wicked Sense Karma is Bitch
People usually take the word “bitch” in a wicked sense. But here’s what it means: “a difficult or unpleasant situation or thing.” or “nightmare.” Consider a statement; Working overtime is a bitch. Replace bitch with the above meaning. So as you now know what bitch really means, let me come back to the question.
The phrase “Karma is a bitch.” rather came from a parallel idiom “Payback’s a bitch.” If a person says payback’s a bitch, they mean that something bad has happened as a result of something else.
The underlying ideology of karma, in lame words, only states; if a person has good intentions, then he will have a good future. If one has bad intentions and does evil things, then he/she has to suffer and payback for it in future. Karma can be applied in both positive and negative sense.