It really depends on the scene and how it's handled. I find gloves an enormous turn-on (especially when black . . . a bit hotter and more sexy-looking than the generic versions). Of course, that might just be because finger-fucking and fisting is so rare in a lot of porn that when gloves are donned, I know I'm going to get a really good focus on that. Plus, I love how fluids and lube shine very visibly on gloves (again, the black ones!), in a way they often don't when on skin. I guess my love for gloves goes beyond enjoying the fact that it's safe sex; I find it hot and sexy all by itself.
Dental dams are a little more "meh". I love the safe sex aspect, but practically, it does hide a lot of the goods. My trade-off is in how well the porn shows the faces of the performers. One of my favorite porn scenes is a long stretch of oral sex with a dental dam- but what makes it so good is that incorporates a good deal of reaction shots. If it was one of the porno's with a close-up shot on the genitals for eons, I'm going to get bored. Watching somebody lick latex generally isn't very interesting. But if the camera shots are sufficiently varied and the performers very into it, they can "overcome" the annoyances caused by the presence of a dental dam.
Condoms are pretty cool by me. I honestly have no preference when it comes to penetration; seeing a wrapped or unwrapped dick makes no difference to me. About the only time I can imagine it "spoiling the fantasy" would be when the porn is clearly supposed to be set in pre-condom times; if you're watching pirates going at it, seeing a condom makes me do a double take and then scoff (but then again, I feel the same way about tattoos and piercings and modern clothing sneaking its way into porn set in the past). I also really wish that more porn actually showed the condom being put on, instead of cutting away to Boom!, insta-condom. When done right, rolling a condom on can be absolutely hot, not to mention that it helps continuity, instead of leaving me scratching my head and realizing that that particular bit was cut and edited out.
I don't like condoms for handjobs (gloves, though, are great!), and I tend to prefer without condoms for oral sex. I like to see cock, and while it doesn't matter much during intercourse, since it's mostly hidden in a pussy or ass, it feels like a shame to hide it otherwise. I can get into it, but I'd just rather have the cock be bare for a blowjob. Oddly enough, though, I pretty much adore condoms on strap-ons; watching someone blow a strap-on with a condom is really hot, probably because, again, I like seeing cock, but don't mind covering up a sex toy.
But really, none of it is a deal-breaker. I'm far more concerned with passion and chemistry and hot sex than whether or not there's a barrier between the bits, and I strongly admire and try to support companies that are able to provide both aforementioned hot sex and a dedication to safe sex.