I've been here since 2007 and is married to a native Vietnamese, and I'm a Vietnamese-American. I know the culture in and out and who to stay away from. I call it as I see it. Certain areas of this country are bad and it's from lack of education and poverty. The current culture that you see in the city is the culture that was brought in from the countryside. People from the north like Hai Phong, Hanoi, Nghe An, Thanh Hoa, are well known among Vietnamese for their lack of fear or respect for law and order. Some of the most serious crimes committed in Vietnam have been done by these people. The drug and prostitution trade here is controlled by Hai Phong gangs; as was in the past. I'm not saying crimes don't exist in other places. The US is much much more violent and dangerous than here. A lot of stuff here are minor borderline annoyances such as purse snatching, pick pocketing, stealing, and taxi meter tampering. A lot of times, the expat let their guards down or carelessly forget to lock their doors, and then find out their whole life got cleaned out. This happens in the places where I mentioned MORE OFTEN than the rest of the Districts. Most of the crimes here are Vietnamese on Vietnamese crimes and every once in a while, an expat is involved. Have I been the victim of any of it? No. Do I know of someone? Yes. Some places are worse than others and it's for a reason. There's an area in Tan Binh where 90 percent of the people are from the North. They speak with perfect northern accents but are born here in HCM city and love to eat dogs just like their northern counterparts. The Vietnamese even have a saying, "The southern people can tolerate a northerner but not the other way around". Go shopping in Hanoi if you don't believe me. A southerner will get hacked just as badly as any tourist. Binh Tan, for example is more independent of governing and that means gvt. and criminals sometimes intertwine. When that happens, all rules including law, morality, and safety are compromised. Districts like 1 and 3 where most of the expats reside and touristy areas are more "uniquely" managed. The gvt. is more involved for obvious reasons.
With that said, there are a lot of good people in this country north or south and they absolutely abhor the behaviors of those mentioned. If you can read in Vietnamese, pick up an issue of Cong An (Police) and you'll know what I'm talking about. I like to save people a some hard time for...karma of course 
Btw: many Vietnamese companies here will not hire people from Thanh Hoa because of their reputation. I hope it clears up a little of my "knowledge".