Bands whose songs all sound so identical, there's literally no point to having written more than one song.
My flatmate's listening to Veronica Falls. It's pleasant enough but every single song or pretty much literally the same - the same production, the same vocal style, the same type of melody, the same instrument mix. So much so that might as well just have recorded one song, released and played it over and over at every gig.
What other bands suffer from a startling lack of diversity?