Thrilling Detective website has an excellent list of "Thundering Cliches" for mystery writers to avoid.
Any story that begins with the P.I. sitting at his desk, drinking from the office bottle.
Any story that begins with a sultry woman walking into a PI's office while he's sitting at his desk, drinking from the office bottle.
Any woman with "legs up to here."
The Mafia. C'mon, guys, get with it. Give the Sicilians a break. There are tons of hard-working Russians, Iranians, Irish, Jamaicians, Hiatians, Greeks, Jews and WASPS who'd like proper respect paid for their great contributions to organized crime.
Arab terrorists (see above).
Any P.I. who flashes a photostat of their license. I mean, photostats? Who uses that term anymore? Hello! It's not 1929, anymore. And by the way, gunsels aren't actually guys with guns...
Excessive references to jazz. Nothing wrong with jazz, really, but jazz snobs are a dime a dozen these days. Anyone fifty or under who listens exclusively to jazz is probably a geek or a snob. It's more likely they grew uplistening to the Stones or the Sex Pistols or Garth Brooks or Elton John or Nirvana or Motown or soul or Public Enemy or the Beatles. And chances are they're still listening to 'em. There's no shame in admitting pop culture exists. Name-dropping Mingus or Charlie Parker doesn't make you an intellectual.
The detective should be a man or woman of their times. At least Amos Walker KNOWS he's an anachronism.
Private eyes who drive classic automobiles or brightly-coloured sports cars. C'mon, forget Magnum, P.I. What sort of idiot tails someone in a car that draws attention to itself? Can't you just see it? "Hey, Mugsy, isn't that the same 1955 cherry-apple red T-Bird convertible in immaculate condition, with the mag wheels and the white pinstriping that was behind us yesterday?" "No, Bugsy, it must be another one."
What's interesting is that I have ready a few contemporary short stories in the larger paying mystery magazine and they contain many of these cliches. Please add any cliches that may have been missed.