Often it's rock with an electronic tinge, or at least a studio-airlessness - suggesting that the music, while it might have electric guitar or bass guitar in it, has been assembled in the studio rather than developed through playing the song at gigs - basically not much adherence to the performance model of the rock band going on here.
examples
what actually made me think of the genre-not-genre is this lot (or person - who knows, who cares?). "Dangerous" sounds to me a bit like DFA if they weren't playing to the hipoisie gallery - DFA if they were more concerned with serious bread than serious cred - DFA coated with some Phoenix-y melodic flair.
(Phoenix - although I had read about them, know they are rated by Pitchforks and Spins and so forth - feel like an archetype for this kind of "faceless rockno bollocks" - electronic but not EDM - tuneful as hell -- but as much as I love "Listomania" when it come on the radio never felt much of an urge to find out anything about them, listen to their albums - which makes me like most radio punters I should imagine)
Another archetypal band-from-nowhere with a song I always turn up is Foster the People "Pumped Up Kicks" - this instantly struck me as a cleaned-up take on Ariel Pink - the vocal, the weak but insistent drums (could almost be mouth-generated), the hazy elegaic production, the wistful melody, even the Dark Lyrics about, what, a school shooter, a Columbine-style misfit?
One hallmark of these bands is they usually have really wack names.
The other big hallmark of these bands that you don't really care if you ever hear anything else by them. Even if the track is wonderful, there's zero investment of expectation for a follow-up.
I suppose F.U.N. would count here
(But I suspect they also have fans, an actual following... )
A key ancestor for all this is "Young Folks" - although this I also heard first through the usual hip channels, where it seemed vaguely in the zone of Sally Shapiro and stuff like that. But certainly "Young Folks" crops up on modern rock stations in LA as a "recent oldie" as if they were just a Big Data / Foster the P type one-off
What a great beat...
Scandinavians do seem good at this kind of thing, or maybe it's more the case that American radio consigns them to this position - ensuring they'll always be the One Radio Hit band, never achieve that sort of Foo Fighters / Tom Petty / Steve Miller dependable-perennial status on rock radio
One of the first examples that caught my ear - Miike Snow, "Animal"
I mean, what is that? How would you genre-assign it? It's not dance music, it's not rock music, it's not what most people think of when they think of pop (Rihanna, Britney, Ariana, et al), it's not indie.... The video has a bit with a drummer bashing away in it but the groove doesn't sound like a real drummer.
All these tunes sound much louder and forceful on the radio, through compression and whatnot, but outside that context, it's wispy stuff. Denatured to the point of insubstance.
But rather that than the vintage-artisanal rock of Black Keys or Jack White's sundry strands of raspage
stop press: another one i meant to include, reminded of its existence by Ricardo in the comments