Not sure how it works in your local state but here in Ontario the health department makes regular unannounced random inspections that include taking temperatures, looking at hygiene practices, cleaning/sanitation practices, food preparation practices and for expired products. They also now require that a certain portion of the staff have a Safe Food Handling certification and to have one of these folks on the schedule at all times.
We also have in a lot of our cities a colour rating with Green / Yellow / Red and a sign hangs in the front window of every restaurant for easy identification for customers. Green meaning all clear, Yellow meaning conditional pass but issues were found and Red meaning the restaurant is closed with major infractions. You can also request to see a copy of their recent health reports and most municipalities will have the information from recent health department visits posted on a website you can visit.
Having owned/operated a restaurant in our family I can tell you that it's quite the easy process when you take reasonable care in terms of food preparation and cleanliness, although we were a bit anal in our care. (OCD in the family).
We always sent sick staff members home and when in doubt on something temperature wise or sanitation wise we would always assume the worst and throw it out or clean it again.
We still had false claims from time to time where people claimed to have gotten sick eating at our place and the health department would come in and do an inspection, take samples of food, and swab surfaces and nothing was ever found.
Most don't know that it can take anywhere from 48 hours up to 2 weeks for symptoms to develop from the typical food-bourne illness unless something is really rancid that was consumed.
That is why the health department has to investigate and wait until a pattern develops where all those sick have eaten at the same establishment in a certain number before they can confirm the source.
Even then it may not have been the restaurants fault, it could be the food products supplied that were contaminated, yet the restaurant gets the bad P.R.