Off the top of my head:
Britney Spears - Britney Jean
Truly a dreadful album from beginning to end, although there are a handful of tracks that could have been good in another lifetime. Work Bitch, Passenger, Alien and Perfume all have potential but are wasted by vocals that were recorded while poor Britney wasn't even in the room. Even on the good tracks, poor production choices and messy Autotune lets down the rest of the song. The rest of the album is a jumbled mess of poorly written filler, D-list collabs (including a duet with her sister which is undeniably the worst song of her career) and a complete lack of any musical direction or concept. Britney was completely checked out of this era, and when you look at the material they gave her to work with I can't blame her in the slightest