I don't think there is much of a backlash against Rihanna, but feel that her last era started off strong and then it got really sloppy and disjointed (especially with that vulgar and pornographic video for "Pour It Up" dropping months after the single had peaked). She needs to step it up the next time around or else it may not go so well.
I don't think there's a backlash against Ke$ha. It's more of a situation where her label picked the wrong singles and she flopped, but she was never overexposed nor did she have a very public scandal or something that led to people hating her. The right solo single at the right time can help her, and with her being in treatment right now for her eating disorder, she has an opportunity for a comeback.
I don't think we can call what is happening with Britney Spears a backlash. The current album was uninspired and served as merely a vehicle for her to have new material to perform during her Vegas show. But it also didn't help things that she did not promote or perform at all that's why the album underperformed. It doesn't make any sense that she and her seem didn't allow for her to perform anywhere when "Work Bitch" was a single. Unless that was a term in the contract that was nonnegotiable or something, but who would agree to such a thing? I think there is still interest amongst her fans and even the general public. She was doing fine for quite a while with little promotion. What worked before won't always work, but the material and promotion really makes a difference.
Regarding Nicki, others have already pointed out how she went Pop and Dance and that definitely alienated some of her core audience. But perhaps it was fluke that she had a crossover when she did. She definitely made some hot records however some of her recent work has been subpar and those fans who were turned off by her change in musical direction might be lost for good. Perhaps with the right single she might be able to have success again, but I think she is over as a Pop artist.
The issue with Taylor Swift is less about the music then being more about how she has reacted to some of her wins and losses in public. The whole "OHMIGAWD! I DIDN'T EXPECT THAT BECKY!" exclamation with her putting her hands in her mouth was cute about 100 awards ago. She needs to stop. Her personal life definitely is playing a role in it as the ways in which she conducted herself have come under scrutiny and she reacted a certain way that was odd. But the real issue is that if I were a Country artist have a problem with the fact that she received a Grammy nom for a non-country song in a Country category. But the issue I do see with her music is that if she continues to go more Pop, she may stop getting nominations at certain awards shows.
I think the issue with Lady Gaga is more about her image being too unusual and that perhaps does not connect well with the general public right now. I think that the lack of visibility this time around may have played a part in her album underperforming. Things have also been very messy with her social media presence and then the issues behind the scenes with her management and the video and remixes for DWUW not being released a timely matter although that is changing with the recent announcement made today. I think that she can make a full comeback, but needs to perhaps tone down her image a little bit to get back, then she can come back with the more outrageous and strange stuff later once she has come back into favor with the public. I don't want her to diminish herself so she can be successful again, but she may need to just for a short time. Not to bring Madonna into this, but after the public backlash over
Erotica, the
Sex book and the
Body of Evidence movie, she did tone it down a bit with the
Bedtime Stories album era after that and she got back into favor with the public and continued to be successful for a while again. Gaga is a great songwriter and lyricist, and she works really hard so she just needs to focus more on the music and then the image can be tailored accordingly and she will be fine.
I don't know why Katy Perry is mentioned in this category as the only remote issue I can see existing is that she is not as strong a live performer which is nothing new. People said the same thing about Paula Abdul im the 80s and she was fine although she hasn't had any musical success in almost 2 decades but she hasn't exactly released anything in that time either. Because she can't deliver consistent performances live every time doesn't necessarily make her any less of a success than she is. What should she do? Lip sync all her performances or should she not do any at all?
Pitbull definitely gets more hate online perhaps because of his recent releases have you been very generic and safe. Back in the day when he was more edgy to experimental but lately it's just like he's phoning it in and I guess he likes that money too much. His formula hasn't changed much from hopping on a current trend, like "Culo" being based on that "Coolie Dance Riddim" that was in the "Pull Up", "Jook Gal (Remix)", and "Move Ya Body" songs, or him hopping on a remix of "Ai Se Eu Te Pego" by Michel TelΓ³ in an effort to cross it over into the U.S. But it isn't that anything and everything he releases automatically does well. He has a fair share of solo and duet/collaboration flops as well so you can't really say that he's doing very well for no reason. And it's possible that those the combination of him plus a certain guest made for the perfect storm and resulted in a success versus a flop at that time.