Stockton is at the low end of the market for sure, there are serve problems like drugs and robberies. I had an instance that some people broke in my property three times in a row while it was under repair, and the police came and told me that they could not do anything. Their suggestion to me is sell and leave :). Also don't expect recovery any time soon, the jobless rate is about 20%.
But still, my limitted experience suggests that it is a do-able time (with interest so low) and area from cash flow point of view. My feeling is that majority of the people are "nice", they would pay rent if they can. Plus, it is a "big" city with a population about 300K and still growing. I think the keys are (1) get good deals (2) good property management (tenant screening). (3) Choose relatively "good" neighborhood. (4) And maybe "good luck"?