If a person sees that he vomits milk in his dream, this dream is not interpreted in a very auspicious way for that person. In general, it is possible to say that a person who vomits milk in his dream is a very sinful person in his worldly life. We can say that a person who vomits milk in a dream disobeys Allah's orders and prohibitions and violates them. It is possible to say that this person is a very sinful person.