Sturgeon's Law

Sturgeon's Law prov.  "Ninety percent of everything is
   crap".  Derived from a quote by science fiction author Theodore
   Sturgeon, who once said, "Sure, 90% of science fiction is crud.
   That's because 90% of everything is crud."  Oddly, when Sturgeon's
   Law is cited, the final word is almost invariably changed to
   `crap'.  Compare {Hanlon's Razor}, {Ninety-Ninety Rule}.
   Though this maxim originated in SF fandom, most hackers recognize
   it and are all too aware of its truth.