... thoughts on Taylor Swift's REPUTATION CD...

For sibilant voices engineers use filters and a mild amount of compression. This is standard practice. 
There may be sibilance thru your speakers due to tipped-up highs from the mix and/or mastering. 

gosta: NOT ON TOPIC - but give a listen to The Eagles 2-disc THE VERY BEST OF, on your 15" woofer Westlakes and APCs

disc 2: track #3 - Victim of Love
             track #13 - Those Shoes

Listen to the beginnings of both; I used to blast these 2 tunes with my mid-50s University S6 (3-way with 15" woofer) - and THEY ROCK !!!
I still use them when testing others' speakers and systems...

Regarding the vocal mushing on 'REPUTATION': it has to be an engineering thing. I am trying to recall clean vocals - I remember some nice stuff on The Dixie Chicks CDs...

... according to what lowrider57 has stated: WITH RECORDED MUSIC - we are never going to truly hear what an/any artist really sounds like...

I know that the days of hearing Harry Chapin with 57 other people in a college cafeteria are gone - real sound is harder and harder to find - but it is a depressing thought that we really don't know what an artist sounds like. Reminds me: My son and I got a reality check when we heard HOOBISTANK live- so so disappointing - AND NOTHING LIKE THE MUSIC WE LISTEN TO ON CD!

Agree. In my opinion nothing that records, analog or digital, is a true representation of reality. It is, almost by definition, a facsimile. Usually in photography this is acknowledged and the goal is not to say: This is the subject as it is but to say this is the subject as I (the photographer) wish you to see it. I have no problem with that in photography or recorded music. In that regard my limited hi-fi pursuit is not a search for what is closest to reality but what is well presented. I think production and recording are nearly as important as the music itself. They can't stand alone but they can compliment and enhance each other.

I'll have to say that The Struts, at least in the small venue I saw them in, got the vocals just right from a live standpoint in that he sounds much a he does on his CDs (even with their fairly low quality). I was frankly astonished how clear and precise his vocal were especially given the raw nature of the performance and the overall (ear damaging) volume. The sound personnel did a fine job and the singer is very consistent.

Unless she was playing in your living room, I'm pretty sure you've actually never heard Taylor Swift's voice without some degree of compression.  It's on all of her albums and live performances.  For example, if you go on YouTube, you'll find a wonderful live solo performance she did of her song "Wildest Dreams" before a small audience at the Grammies, just her and a Fender Jaguar.  It sounds great and natural, but it's loaded with compression and plate-type reverb, which has a similar sustaining effect as compression.  You may not notice it, and that's a sign that it's well done, but it's all there.  In fact, as I think about it, you may have noticed it more on the the Red album than on Reputation, because Red is not as completely synth based as Reputation, so  the vocal compression may stand out a little more.  One of the interesting things about current synth based, beats oriented music is that it is not intended to sound "real" or like anything other than what it is.  So concepts like compression and DR reduction are pretty meaningless, Because, compared to what  . . . ?

It may have all started out a a radio volume thing, but now it is just the sound of modern pop music.  And it can, and often is, overdone, for example with many current country music releases, which are so compressed they sound like they were squeezed out of a tube.  But it is always there.  So much so that I would have to disagree with the previous poster who said there is nothing inherent in the music that requires it.  As a factual matter, there is.  The classic rock and pop recordings from the 1960's onward were all recorded through microphones, guitar amps, mixing decks and tape recorders that each furnished their own degrees and flavors of compression and saturation.  They were also run through compressors and limiters like the UA 1176, Teletronix LA-2 and Fairchild, among others.  All of those same devices (or more often  digital emulations) are still used today.  Sometimes it's not used well and it doesn't always sound so great through the fancy equipment owned by the folks on Audiogon, but from the Beatles to Taylor Swift, it's the sound of pop and rock.