With mouth-watering names like Roll'n Lobster, Belly Bombz and the Pudding Truck, food trucks are irresistible. Especially when they’re parked right outside your office at lunchtime or lined up at a festival. Whether you want BBQ or a vegan sandwich, you can find it at a food truck.

But how safe is the food they sell? Are you risking getting sick from a food-borne illness?

Here, what to know about food truck safety standards, outbreaks traced back to food trucks and when to walk away.

Related: 5 Ways to Tell if a Restaurant Isn't Clean

Dirty hands, dirty counters

The California Environmental Health Specialists Network (EHS-Net) program assessed 95 mobile food trucks operating in six counties. The researchers looked at risk factors for foodborne illness, including improper temperatures, poor personal hygiene of workers and unsanitary food handling.

The results: 90 of 95 mobile food trucks had at least one critical risk factor that boosted the chances of food-borne illness. The findings were reprinted in 2014 in the Journal of Environmental Health.

The most common problem found was food truck workers not washing their hands, or not washing them well enough. Next was inadequate sanitizing of surfaces, cross contamination of foods (such as raw meat making contact with a meat sandwich that's been cooked and is ready to serve), inadequate refrigeration and food temperatures that were too high for foods meant to be served cold.

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Of course, sit-down restaurants are subject to some of the same potential risk factors, the authors note. The difference, they say, is how, and how often, food trucks are inspected.

The researchers surveyed 57 environmental health agencies and found they typically conducted only one inspection a year — a scheduled one — due to lack of manpower. Another challenge inspectors face is the difficulty of inspecting trucks while they are in operation, as their routes change often.

The findings, say the researchers, point to the need to conduct mobile food truck inspections the same as inspections for traditional restaurants, which ideally are unscheduled, ''surprise'' inspections conducted while the restaurants are open for business.

Health officials shut down trucks once they trace a food-borne illness outbreak to them. Officials in Washington state shut down food trucks earlier this year after an E. coli outbreak that reportedly sickened at least nine people. They cited foods held at unsafe temperatures and cross-contamination among the problems.

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Would your favorite food truck pass inspection?

There’s no way to tell for sure whether the food you buy at a food truck is safe, but you can up the odds of buying from a safe truck with these tips.

Make sure it’s licensed. Multiple state and local agencies regulate food trucks, so regulations vary greatly across the country, but the trucks typically need a license or a permit. Some trucks display their license on the side of the truck. If it is not there, ask to see it, suggests Robert Brackett, PhD, a certified food scientist, spokesperson for the Institute of Food Technologists and director of the Institute for Food Safety and Health at the Illinois Institute of Technology.

Look for a letter grade. In some communities, the trucks are given letter grades after inspections. For instance, in 2013 officials in Louisville, Kentucky, began giving food trucks the same A, B or C placards given to restaurants.

Notice how the forks, knives and spoons are displayed. Handles up is best, says Jeff Nelken, RD, a food safety coach and food safety consultant to the restaurant and hospitality industry. That way, people haven't pawed the part of the utensil that will have contact with your food or your mouth.

Communal condiments? Individual packets are best, Nelken says. Containers that are multi-serve but look clean are next best.

What comes between the server and your food? According to the CDC, food workers should avoid touching food directly with their bare hands. Expect them to use gloves, wax paper, tongs or other utensils.

Does the staff look clean? Do they have their hair pulled back and not tangling over the food? If they’re not wearing gloves, do their hands and fingernails look clean? Nelken says these things matter. 

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Kathleen Doheny is a Los Angeles journalist specializing in health, behavior and fitness topics.