You might want to check out how your day care center deals with ill children. I've seen places where a child was feverish at 4pm and brought back in bright and early the next morning even though "the policy" states 24 hours free from fever.
Has it been so ingrained that the teachers automatically wash their hands numerous times per day? Have the children been taught to wash their hands after they potty or wipe their noses? If this is enforced, most children will do it automatically. How often are surfaces and toys sanitized?
Do children who seem ill remain in the classroom until a parent arrives, or are they moved somewhere else (typically the director's office)?
From what I've seen, most places are lax. The teachers will be ones who will tell you the truth, not the Director. The teachers don't want to get sick either and they are usually the ones pressing to have a sick child removed, while the Director don't want to take a stand and insist a parent leave work, and stay home a day or two while a child recovers.