Sturgeon's Law is an adage derived from a quote by science fiction author Theodore Sturgeon: Ninety percent of everything is crud.
Origin
Theodore Sturgeon replied to a fan who wondered why he wrote science fiction when he was a skilled writer of other genres, "Sure, ninety percent of science fiction is crud. That's because ninety percent of everything is crud."
Alternation
Sturgeon's Law is often cited using crap or shit instead of crud. The percentage figure also sometimes varies, having been in print as "94%".
Interpretations
Sturgeon's Law may be regarded as an instance of the Pareto principle.
See also