Chances of Visa application

Hi, my friend has previously worked in China but he has criminal record in PRC now. Although he is not deported as his wife is a local chinese and he still manages to get a temporary family stay type (of around 6months each time). My query is, what are the chances of him getting a working/business type if he managed to have an employer in China? Will his criminal record affect his chances of getting visa? If so, what are the chances of getting it? Can an indication that his wife is a local chinese aid in the approval chances?