The German employment reference

Read literally, Er hat sich stets bemüht is a generous sentence: he always made an effort. In a German reference it is one of the harshest things an employer can put in writing, and it is meant to be read that way. The idiom works by substitution. A reference is expected to report what somebody achieved; when it reports only what they attempted, the reader concludes that the attempt is all there was. The adverb makes matters worse rather than better. Elsewhere in a reference stets lifts a sentence, but attached to trying it only confirms that the trying went on and on without arriving anywhere. So learn sich stets bemühen as a fixed phrase with a fixed meaning, not as the sum of its words. The rest of this list gives the vocabulary a reference is built from, which is what makes a sentence that avoids it stand out.