A reviewer is going to have some biases. We're people, our likes and dislikes are going to show. Sometimes you can get past the issues, sometimes you can't. It isn't reasonable to expect total objectivity when your big squick button has just been pressed. Sometimes all you can do is back away slowly. I just read a remark from another reviewer about how the treatment of race in a particular book made her decide against reviewing it, because she didn't trust herself to be objective. It made sense to me.
I should tell you what my problem issues are and how I plan to handle this.
First off, I will tell you in a review if one of those issues crops up. I won't let you guess if it's the theme or if it's the writing. In a recent review, I've had to identify one story that I couldn't finish and why, and it had nothing to do with the quality of the writing. In another, I had to admit that the entire setting (BDSM) makes me uncomfortable. And I liked the story after all. I do try to be fair, and if I can't be fair, I'll be honest.
Soul mates -- this one hits the gag reflex, no matter what the writing looks like. It screeches me to a stop 99 times out of a hundred, and the hundredth one is probably involving a non-human. Apologies to writers who use it and readers who like it, but it strikes me as a stupid, cheap plot device, and I hate it in real life, too, where it was definitely a stupid, cheap device. You may never see a soul mate story mentioned in this blog unless it would be leaving out one story in a collection. And then I will say why it was a DNF.
A more general kind of "mates" I can enjoy, if it's personalities first, then the bonding. But the whole "you are fated to be with this person and this person only" thing will get a fast exit. Or whining if it got sprung on me late.
Rape/incest -- rape doesn't usually turn up in romances except as some past trauma, which is fine, I can do without that altogether. Even then, the bunglings in fanfiction have left me jumpy -- it's usually not handled well and if it's not, I WILL mark it against the story. Count on it.
Incest- also a problem. I buy my reading material and so most of this is won't get past at the cash register, but if you hear some faint voice shrieking, "oh hell no!" it's probably me reading a blurb with identical twins.
BDSM -- this one is trickier because I'm not a fan of the kink and mostly just find it sad or upsetting, but every now and then there's a story that I like, which isn't to say that I read all the way through. It doesn't come up often, because of that cash register thing, but it could, and I will remind you that I have issues, and then you can grind as much salt on my words as you need to. But I won't mark down a story just for being BDSM -- all the other stuff has to work
Crap editing: sometimes this is hard to tell from crap storytelling, because not every house out there edits as much, but I'll notice. Sentences that lie there on the page like a nest of garter snakes get noticed too. Sometimes out loud. Some lapses in line editing I can overlook, but it's sloppy and makes me wonder. This isn't exactly a "have to flag thing", but it can cost a story half a marble if there's a lot because it interferes with reading
I WILL notice logic-fail out loud. And if I can't find the plot beyond "hawt guys fuck" you can call me Cryssy Crankypants.