Whenever I travel to Thailand (I realize that you are not in Thailand but I have never been to your country) everyone talks about the late night nature of 7-11 and how it is just a part of everyone's life. As far as I know, there are zero 7-11's in Vietnam and we don't really have an equivalent.
I think the main danger of 7-11 is that almost everything they sell in there is food that is absolutely terrible for you.