Dialogue is cliched, the acting aches and the locations are boring.
For a television murder mystery to work its odd magic, an audience has to be made to care enough to sit, all out of breath, all the way through to that bit at the end where the killer is revealed and the detective made brilliant.
The more charismatic the detective is the better, of course, and that doesn't mean svelte and good-looking. Being porky and dishevelled often works better and it's usual, too, for the detective to have some sort of sidekick - preferably someone not porky and dishevelled.
It's excellent also if there's a nice new murder mystery in each episode and that they're all set in the same locale. A village or small town works well, though the viewer can begin wondering how such small places can survive the sort of death tolls these series demand.
Detective shows have worked wonders with TV ratings for decades now and they've often - overseas at least been granted kingly budgets and taken to giddy heights of style and star-studdedness, like the impeccable British-made Poirot, which finally departed this world just recently, after 25 series.
I don't imagine The Brokenwood Mysteries will run so long. It's a local version aiming at that grand TV detective tradition and it kicked off for a tentative short series on Prime on Sunday at a confident 8.30pm.
There's not a lot of reason for such confidence. The opening two-hour episode set the scene with many of the usual suspects, including the pudgy dishevelled detective in the lead role, this time with a cute young sidekick who doesn't share his weaknesses for country music cassettes and old Holdens.
Apart from a brief but unresolved conversation with one of the story's corpses, that was really about as interesting as Detective Inspector Mike Shepherd really got.
And the country music, sadly, wasn't even Tammy Wynette, but something more affordable.
Which is what it comes down to, I suppose. Because The Brokenwood Mysteries isn't really very good, the acting often aches and the setting - a touch of Warkworth here, a hint of Helensville there - isn't all that dark, dangerous or interesting.
The hero is rather light of voice and his character light of any interesting vice or alarming inner twitch, apart from some nonsense about how many ex-wives he might have.
Some of the dialogue must have come from a kit. There are several "For the record, where were you last night?", the ever-popular "I just need 24 hours", a "Mind if I have a look round?" or two, not to mention, "We're going to have to sort this out down at the station".
It's down at the station where new-to-town Inspector Shepherd finds that cute sidekick, Detective Kirsten Sims, played by Fern Sutherland.
And Shepherd no sooner hits town than the murdering starts, which is the way it goes with these sorts of shows. There's a drunk farmer, dead off a picturesque bridge, and a woman, deceased in a ditch by a green winding country road. And there are an awful lot of people to suspect.
"Things have livened up since you arrived," someone observes after the second murder.
That first episode - there are three to come - went for two hours, and, as I might have mentioned, I'm glad it wasn't longer.