I know that the word BAD is used for something that is wrong, as evil, inadequate, incorrect, etc., but what is its meaning when it is used in the expression: I want you so bad.
I want you so bad, may be gramatically correct, but it is a deviation from established convention that wish/want/ desire are used for expressing positive things, for instance
I want to see you as a good business man.
I wish that you should get a rank in examination.
I desire that I should be the topper.
Like-wise, Want should always be associated with wishful thinking.