How dark is too dark?

As many of you know, generally speaking I'm primarily a romance reader. A genre well known for it's happily ever after (HEA) requirement. No matter how dark and difficult the journey gets the romance reader slogs on secure in the eventual HEA. Other genres have their own parameters: the mystery must be solved, the evil henchmen will be foiled or apprehended or killed, the quest successfully completed, etc. Lately I've been reading mysteries (police procedurals) written by international authors. I've enjoyed my little jaunt outside of my favorite reading, but my most recent read (review coming soon) has left me wondering about my preferences in tone and characterization.

Generally, police procedurals is a self explanatory type of mystery, one definition found here. A few days ago I finished a PP written by a new to me Irish writer.It was absolutely excellent & I hope to find/buy/borrow his other books via the library. However, the protagonist is a man who is willing to bend events and statements to suit his ideas about who is guilty. I found this protagonist's personality & moral compass very troubling. I don't plan to dissect this book here. I'm trying to think out loud, as it were, about my own parameters regarding protagonists in fiction.

For certain things I have strict preferences about characters & personality type. One example would be vampires in paranormal romance. I will read only those vampires (male or female) who are confident in their "vampireness", who are not looking to redeem their lost souls, who have no more regrets than the rest of us. I will not read any angst laden, guilt ridden, OMG I need my soul back vampires. The recent trend in hard assed, edgy, take no prisoners, I don't need help dammit female protags? I'm tired of these chicks, already. I need to empathize with the lead character, people. I need some kind of hook to hang my hat on.

I'm new to the police procedural subgenre. I've only read & watched a few. Watched more than read. Maigret, Kurt Wallander, Montalbano, etc. I'm thinking that the cookie cutter problem solver in a PP has some of the following: divorce, past/current addiction, tormented childhood, failed love relationships, estranged children, money problems. I expect all those. Sherlock Holmes, one of the greatest detectives in fiction, is an addict and a misogynist.

In my limited exposure, though, the underlying compulsion is a thirst for justice, a desire to solve the puzzle, a tendency to hunt down the truth- whatever. Something like that. A type of single mindedness that often excludes much else from their personal life. Until now I've not come across a PP wherein the protag turns out to be, at best, morally ambivalent regarding how he solves his puzzles at worst, a contributor to the moral malaise modern culture is said to suffer from.

Plainly said, I don't like him. He's morally repugnant. He's actually a bad guy. Deeply & truly bad, not bad with a heart of gold bad. Know what I mean? The book police guy is like Michael Chiklis' character on the tv show The Shield. A good guy in name only. In a charming way, truth be told. If you read the 'definitions' of police procedural and noir, I guess this guy moves this book firmly into the noir end of the spectrum. As I said, the book review comes later.

Uh, I guess the short version is: I dislike reading about morally ambiguous main characters. So, most people would/have/are ask(-ed, -ing), "who cares, woman?! move on already!" Somehow I feel like it's my shortcoming as a reader that I dislike negative characters. That I'm supposed to be ok with all types of character immorality. Has reading romance so long narrowed my view that much? Or ..? Maybe (probably) I'm just a simple minded reader who prefers things more clearly white and grey and less definitively black. There's enough evil and darkness IRL anyway.

I guess what it comes down to is that, in a dark toned book, regardless of genre, I need there to be some small amount of light in a primary character in order to keep me going. For example, in the Black Jewels trilogy, Saetan & his love for Jaenelle kept me going in the pitch darkness that series sometimes led me into. There are other books where I've disliked a character's morals enough that I've dropped it unfinished. What does it say about me that I've finished (barely) Madame Bovary but can't quite get up enough nerve to read Anna Karenina?