Justin E. H. Smith at his own site:
I strongly suspect that at least 95% of occurrences of the phrase ‘a murder of crows’ are found in sentences like, “Did you know that a group of crows is called a ‘murder of crows’?” With this in mind, it can’t really be correct to say that a group of crows is a murder; the preponderance of occurrences of the term in sentences of the sort I just gave means that, in the other 5%, the ones where English-speakers say things like, “Look at that murder of crows,” what is in fact happening is that the speaker is drawing attention to the fact that he or she has mastered this precious bit of vocabulary. The focus of the proposition, in other words, is the speaker, and not the crows.
The more attentive you are to questions of style in language, the more you become attuned to the fact that a great deal of it works in this way. As far as I can tell no one actually uses the word ‘temblor’; it is a hack synonym for journalists to throw in when they have already used the word ‘earthquake’ too many times, and need to show a capacity for variety. I’ve long suspected that people almost never use certain anatomical orthophemisms in a way that faithfully focuses the listener’s attention on the denotation of the term, but instead that whenever we hear ‘penis’ or ‘vagina’, what we’re actually hearing is a sort of performance of the speaker’s maturity. (As I’ve pointed out before, both of these, as well as ‘anus’, have their origins in Latin euphemisms: ‘tail’, ‘sheath’, and ‘ring’, respectively). I never use these words anyway, but always talk around them, aware that they pose an objective and irresolvable problem to anyone who cares about language, and understands that real mastery of language is not just about getting things right, but calibrating one’s expression of what is right so as to allow its performative aspect to be evident only as much as one wishes. A hack by contrast is someone who uses words like ‘temblor’ or ‘penis’, or phrases like ‘to tamp down’, and thinks they’re getting away with it.