I only worked in one food service facility -- Subway.
Things were bleached every night to kill bacteria and to keep the white accessories (like those cutting boards) white.
The floors were swept as needed, the walls were washed as needed, the floors were mopped nightly, and, the tables were cleaned as used. The trash bags were removed as needed throughout the day, and piled in the back to be taken out each night.
I never once saw a mouse, or any other rodent. There was no evidence of rodents, either.
I never once saw an ant, although, ants are a common problem in the area.
We did get flies. They'd come in as people came through the door. Not much one can do about them. We got good at killing them, however
We once had a cockroach. It was very weird. We had left the back door open because the a/c wasn't working. Then there was a cockroach. The owner found it and killed it. About two hours later, an exterminater came around, handed the owner his card, and said he was new to the area and was giving out special rates. Then he asked if there had been any "insect problems".
Yeah, we had the schmuck fumigate, but, I think the owners realized afterwards that he had placed the roach in the back of our store. Afterall, in the five years they had been there, they had never seen a cockroach. And they never saw one again afterwards, either.
Does shit happen? Yes, but, then you call in exterminators who get rid of whatever pest there is, and you do it right away.
The store will only be as clean as its management. Our management would drive us crazy if we received anything less than 100 on our health inspections. If things broke (like tiles -- that'll lose ya points quickly) they were repaired. Basically, that's what you lose points for -- pests, disrepair, unsafe handling proceedures (temperature is wrong, food left out, chemicals near food, etc). or not having sinks/soap/paper towels available.
It's not difficult to keep a restaurant clean. It's just like your home, but, with more business. You have to use the same practices, if not more stringent ones.
The attitude of "when in doubt, throw it out" helps too.