The CDC estimates that every year 48 million people get sick and 3,000 are killed due to foodborne diseases. And, according to a study that took place in Seattle, restaurants with poor inspection results and violations of proper temperature controls were "between five and ten times more likely to have foodborne illness outbreaks."

The above map shows inspection ratings by restaurant in Seattle. I wouldn't take it to mean much if a restaurant received an "unsatisfactory" score on a couple of inspections, but a low percentage of satisfactory ratings at a restaurant with multiple inspections might raise some questions.

Data:
King County GIS Portal
*Legal: These data are public and were last updated June, 2016. They are not modified from the source in any way to defame anyone, and, to the best of my knowledge, true. But any large database will have plenty of errors. Contact me if something is inaccurate and I will fix it ASAP. Otherwise, I'm covered.