Said conclusion is that Deanna hadn't changed substantively since middle school. As I've speculated in the past, it's very likely that Mira had spent a lot of her free time wondering what miscalculation on her part lead to Deanna growing up without any sense of empathy, any idea of right or wrong that wasn't based on maximizing her personal comfort, damn the cost to anyone else or even the least hint of self-awareness. She might have thought exposing her daughter to genuine want might have kick-started a sense of morality that wasn't predicated on not having to do things she didn't feel like, not having to care about concerns that made her own life a bit harder than she'd have liked. Sadly, shipping her off to Honduras took as well as music lessons. This meant that poor little April is thought of as being a natural-born serf because Deanna is and always has been Daddy's Little Sociopath, perfectly capable of listing everyone else's flaws in smug self-satisfaction while screaming in rage if someone questions her own perfection. This also makes Michael a figure of pity.
Elizabeth, on the other hand, would strike her as someone to be feared. Trying to convince the Pattersons to adopt a color scheme that wouldn't be regarded as distastefully vulgar by the idiots on Jersey Shore would have given her enough exposure to the middle Patterson daughter to realize that Lizardbreath is an oblivious, self-absorbed idiot bitch who doesn't have the least idea of the damage she's done to other people in her doomed quest to have her Daddy and Mommy finally love her. While her dim, sullen clod of a son-in-law might have a distorted idea of what happened to Therese and can, if asked, see that there are people who might empathize with her and hate his sister, the idea of feeling pity for the woman she's replacing is as alien to her as seeing that maybe she'd like to at least participate in a big wedding so she can feel as if she didn't let her own parents down made no sense to Deanna. In both cases, a self-important jerk is throwing her weight around like a dumb bully and playing the victim.
The reason that she'd be terrified is that Anthony is the same damned sort of person Liz is. The same feeling of being a victim, the same need to tyrannize and the same lack of empathy or proportion animate both idiots. This means that while Mike and Elly's vestigial sense of morality might lead them to ask horrible questions of themselves and maybe even feel bad about outrages like the Housening, Liz and Anthony's cult of victimization would allow them to dare any distasteful thing in the smug belief that the horror others are revolted by is a wonder to be envied.