Secret: A dirty bathroom means a dirty kitchen.
Although it may seem counterintuitive to associate a restaurant’s bathroom with their kitchen, these two places often share the same level of cleanliness. If a restaurant can’t be bothered to keep the toilets and sinks clean, then imagine what their refrigeration and workspaces look like in the kitchen.
Solution: Do not eat at a restaurant where the bathroom trashcan is more than half full. Is there toilet paper? Is there soap? No? This means the bathrooms are not being regularly monitored and cleaned.