Alejandro, TEOG music video & whatever happened behind the scenes, getting rid of Dada for whatever reason, hiring her friends to do things professionals should be doing, and hiring LaurieAnn as her new creative director. Those are all of the recent things I could think of.
"Oops!...I Did It Again:" Releasing "Don't Let Me Be The Last To Know"/Not releasing "What U See (Is What U Get)" and "Can't Make You Love Me"
"Britney:" Releasing "I Love Rock 'N' Roll"/Not releasing "Lonely" and "Cinderella"/Choosing Pepsi over ClearChannel for the tour sponsor
"In The Zone:" Not releasing "(I Got That) Boom Boom"/Releasing "Me Against The Music" as the lead single over "Toxic"
"Blackout:" Picking that awful album/single cover/Performing at the VMAs/Not releasing "Radar" and "Hot As Ice"
"Circus:" Not promoting/Releasing "Radar"/Not releasing "Shattered Glass" and "Unusual You"
"Femme Fatale:" Not promoting/Lip-syncing during TV performances (when she can clearly sing as she does on tour)/*reserved for all the mistakes that have yet to happen*
Rihanna: Joining Twitter, dating certain people, not releasing "Fire Bomb", releasing "Rockstar 101", "Man Down" and "California King Bed" being released at the same time, "Breakin' Dishes" and "Wait Your Turn" not being released as proper singles, Music Of The Sun only having 2 singles, and releasing Rated R and Loud in the fall.
Britney: Releasing "Radar" (yes, I know her label had to), not completing the "Outrageous" video, not releasing atleast one more single from Blackout, "Telephone" missing from the final tracklisting for Circus, the tragic "Break The Ice" video, and remaining with Jive for so many years.
Hole: Courtney attempting to revive the band with all new members (seriously, there is no Hole without Eric Erlandson), the extreme lack of promotion for Nobody's Daughter, the final tracklisting for Nobody's Daughter, and the lack of videos this era.
Sky Ferreira: Everything. Everything about her career is a mistake, and it's all because her label is a piece of **** and won't let her have even the slightest bit of control over what is and isn't released. I hope she finds a new label.
Muse: For god's sake, how did "Exo-Politics" never see a single release? I realize that BHAR was an album full of singles, but jesus, that was one of the most instantly marketable.
It's a nice song, but the released singles of this album were OK already. No need to release this
GaGa: Not waiting for Judas to hit number one or at least get a new peak, Releasing the Alejandro video, Born This Way video, having the Haus do things that professionals could do better.
Rihanna: Dating Chris Brown, concurrently releasing CKB and MD, not promoting Russian Roulette better