I've disengaged completely and don't even feel bad. I cannot stand DHs kid and cringe at the thought of her. If I didn't have a baby with him, I would FLEE. 

Take solace in knowing that you're not alone in your feelings.  I think this is the only place that we are free to state how much we dislike a minor child without other parents clutching their pearls and looking at us like we have 3 heads.  However, its the parents that make these kids just unlikeable!  
I told my ex several times that his kid was just not a likeable person and the reason that he has zero friends and most adults dont even want to be around him.   At least mine understood that he had an issue on his hands, just refused to do anything about it for fear of hurting the feefees.  I raised a daughter so I went through all these same years that these men are going through and not saying that I never had any issues with my daugther, but she was never an unlikeable person, had friends and was able to hold a conversation with an adult while acting mature.  As well she had male friends that I would regularly witness how they acted and never did I see any sort of behaviors that these newer kids are acting now.  
How these men can live with themselves and not be completely and utterly embarrassed and shameful as to what they have raised is beyond me but yes, without the parent willing to do anything then they do become unlikeable human beings and I dont think we should feel bad about saying so.  They may be minor children, but by a certain point they have a full understanding of how their behavior affects others and awareness of such.

I think many stepparents profess feeling love towards their stepkids when they don't really. 

My feelings for my stepkids have only deteriorated over the years, both due to personality and situation. 

Both of my stepkids are boring and entitled. They basically come to our home and expect to be catered to. They also have no interests outside of YouTube and XBox, so can't even have conversations with them.

Everyone has a right to thier feelings. Just as there are adults we dislike or don't get along with. I dont understand why it's such taboo to feel the same way about kids. I would never condone mistreating a child or teenager, sometimes the best you can do is maintain a civil relationship with someone but never develop a closeness for whatever reason.

I do not blame myself for my feelings towards SD, she is a very mean spirited person. I joke all the time that she reminds me so much the popular blonde girl in that movie Mean Girls. 

I like OSD and I was very close with SS from my last relationship, we still keep in touch and I always cared about him like he was my own.

I feel the same. I can't stand SD and it's because of her repulsive personality. SS is a normal kid and tolerable. I don't ever foresee myself having a relationship with her.

As someone said above, my feelings for SD9 have deteriorated over the years. I overlooked a lot of her awful personality traits and odd behavior when my SO and I first got together. I was too focused on being the mom that she didn't have. Recently, we watched home videos of her when she was four and there were already signs that she was going to end up being a fake, dramatic, rebellious, attention-seeking narcissist. Now that she's nearing ten years old, it's apparent that she's going to be just like her BM and her other crazy blood relatives... regardless of who is raising her. I don't feel bad for not being able to stand her, and you shouldn't feel bad for feeling that way either. It is what it is.