Sturgeon's Law is along the lines that - for any given field of endeavour, or Life itself - 90% of what comes-out is crap.
It's intention was, apparently, to argue that even when there is good, worthwhile, valid work to be found - say, in science fiction writing - nonetheless, the bulk of work in the field will be crap: but that 90% of crap ought not to put us off engaging the whole field. We should, it is implied, simply seek-out the good-stuff and ignore the crap.
Another example is that even in the time of Shakespeare, most of the plays written were crap; and indeed a lot of Shakespeare's own output was crap: as is indeed the case for Mozart (who is highly regarded for relatively very few, sublime late pieces from the hundreds of bits of trivial crap that he wrote). I daresay (and this is implied in Plato's dialogues, in reference to the sophists) the large majority of Athenian philosophers at the time of Socrates were mere crap-spouters... but then there was Socrates, there was Plato... and so Greek philosophy was redeemed.
Maybe this used-to be true - but the Law became popular at a time when it had become false; because 100% of most things is crap.
My impression is that people cite Sturgeon's Law to mean something-like the opposite of its original intent: - they use it to suggest that in any field of obvious crap - such as the modern mass media, mainstream politics, professional science, classical music - there will always be some (?10%) of truth, virtue, beauty, worthwhileness. Yet in these examples there is only crap.
The presence of vast volumes of crap does not - in any way - guarantee the presence of gold in its midst. Just because most of what is produced is always crap, this does Not mean that any of the crap is any good: most crap is simply that - and nothing else.
And this shouldn't be a surprise - because it is hard for anything Good to survive in an unceasing torrent of crap; and therefore, mostly, it does Not survive.
