Thanks for the feedback! It means we have to improve the FAQ on this part.
Hosts cook and eat with their guests, so it's a very good way to be sure about the quality: First because hosts eat it as well, second because they'll have a direct feedback, and it's not very pleasant to serve bad food to people when they're eating with you.
In fact, we think there's a fear of a risk more than a real risk. There's less risk to eat something that has been cooked at home, in smal quantities, than something in a big restaurant with food that has stayed in a fridge for several weeks...
Actually, have you often been sick when invited by friend or family?
Reviews we're doing are based on information provided by hosts (description, pictures), as well as email or phone contact if needed. And the review system will help. Risk averse foodies will eat with hosts with no reviews, less risk averse will go to hosts that already have a good reputation on the system.