Why would a man say this?

the woman is no good for no man, and i have no respect for her?

Because the man in question has no respect for the woman in question and feels that she has a negative impact on individuals of the male sex.

im not good with volcabulary, what do you mean negative impact on the male sex

It could mean lots of things. I don't know the woman so I couldn't be specific but maybe she plays with men's hearts, maybe she is a cheater, maybe she likes to have men do/pay for every thing for her. She could use them and then leave them. She could cry a lot and make them feel guilty about things that he should not feel guilty for. But what ever the specifics it is sure that the man who spoke this thinks that she is bad for men in general.

thank you coldsnowbunny, it makes sense. this is all to do with my previous posts "how to take this quote "nothing really happenend, it was all innocent"