It's hard for me to describe my feelings exactly but I'll try. And the only way I know how is by concrete example to back up what might otherwise seem somewhat abstract. I have declined to read the following books for the reasons briefly indicated (beginning with the one that lead to an enormous brawl here some time back)
The Ice Man - because a criminal sociopath, who was a hired killer with 50 cold-blooded murders to his 'credit,' and who psychologically and emotionally tortured his young daughter, was described as "a good father;"
The Beautiful Bones - because it described the rape-murder of a young girl;
On Chesil Beach - because it featured tight-focus on the consummation of a marriage on the nuptial night (to use archaic language);
Never Let Me Go - because it dealt with deliberate cultivation of human beings in order to harvest of their organs and leave them dead.
A Long Way Gone - because it deals with a child learning to commit "truly terrible acts" (a euphemism including atrocities?)
As one can see there are a variety of individual underlying reasons of all sorts. Murder, rape, sex, criminality, human degradation are not specifically off my radar screen, in and off themselves. Although they are certainly far from my first choices. I suppose my rebellion is against reading about evil that is used to propel a larger story that capitalizes on it or otherwise frames it in some apologetic sense.
In the case of "A Long Way Gone," I could imagine reading the contemporaneous narration by a boy-killer himself of his activities in a non-fictional account -- a newspaper interview for example. I'm sure we would see a reality we couldn't imagine. I find it harder to go for an account where the author has now had the benefit of 14 years of delay and hindsight to adjust and present his story to us in a light well chosen by him to show his final achievement of redemption. My mind boggles.
In short, I guess I reject the use of evil as a tool to propel a larger story of different intent. 'Sensationalism' might be the word that comes to mind, although I lack for a good one.
Separately, there is a person at another site that I visit who has a vitriolic scorn of authors who use events of the Holocaust as a backdrop to provide 'color' for novels which ultimately are for 'entertainment' in the broader sense of the word. I think that is an ultimate example and I completely understand his view point. The Holocaust was an evil that should only be treated in the context of evil. And he would say preferably by reading (only) direct accounts of Holocaust survivors and witnesses, not second-hand accounts by hucksters of fictional stories such as Omega Minor, which was the case in point.
So those are my unfocused but definite reactions to this sub-genre.
PS Sorry for the cross-post. I didn't see the previous two posts while I was typing. But as for the list, by all means leave it on and let people vote on what they wish to read. I do not wish in any sense to be a censor here. I only have one vote like anyone else. And I was only answering a question about my own reasoning.