There was not really a rule that governed Ye Shuang's working habit. As she said earlier, she was not in a position to be choosy about her clients. If Chen He offered a case second after her contract with An Zining ended, as long as the content was not too ridiculous, Ye Shuang would accept it. The history and moral judgement of her clients had nothing to do with her.
In other words, Ye Shuang would not be loyal to only one client. However, that did not mean that Ye Shuang did not have her own moral code to abide by.
Things like selling the information of her former clients was something one should not do. Furthermore, this was illegal by law. Han Chu had stressed this to her when he signed the contract with her, and Ye Shuang personally agreed with the law.