It is the price you pay for cheap food - a lack of hygiene and food-safety practices.
At least this is the unquestioned, conventional wisdom.
And this is true of all people who eat out on very limited budgets, including college students - an affordable meal does not mean safe, clean food.
A year ago, this question was asked by "Action for the City," a local NGO which launched a project called "Students Voting for Restaurants," which had students rate the level of cleanliness among food vendors near their universities.
The project has helped students take part in an online voting system to decide their favorite budget restaurants based on a set of food-safety related criteria, provide comments and upload pictures about their favorite places.
But funding is running out and according to Nguyen Huong Giang, director of "Action for the City", they are hoping to train volunteer student teams to continue the work.
Tran Bao Thoa, a student from the University of Natural Sciences, said at first, many restaurant owners refused to take part in the project, fearing they would incur losses.
The project's volunteers then had to pretend to be guests in order to record images of places violating food safety.
The upshot of it all was that many owners agreed to improve food hygiene in their establishments.
Some of the criteria looked at include wearing gloves and aprons while serving, cleaning serving counters and storing food in stands that are at least 75 cm above the ground.
The project idea was awarded a prize at the World Bank Innovation Day 2008 for encouraging young people to exercise their consumer power.