I just found this: http://www.docguide.com/dgc.nsf/html/English-...
Main Entry: bill of health
1 : a certificate given to the ship's master at the time of leaving port that indicates the state of health of a ship's company and of a port with regard to infectious diseases
(I never knew about this.)
2 : a usually favorable report following an examination or investigation <gave the criticized textbook a clean bill of health>
OK. Since "bill of health" is USUALLY a favorable report, a "clean bill of health" must be:
A good/favorable/spotless report. I was searching for another way to say the example sentence in English, hoping it would give German-speakers other ideas:
The Health and Safety Executive rated its operations as completely acceptable.
The Health and Safety Executive rated its operations as first-rate.
The Health and Safety Executive said that its operations violated no laws.
I don't really like ANY of these alternatives, but the point is that if it is so hard to come up with an alternate term in English, it must be a nightmare to translate it.
By the way, if a textbook gets a "clean bill of health", it means Texas has no objections. And that is NO joke.