Yeah. I mean sure, some of the sisters are better than others. Lori is a bitch, Lynn is a butch lesbian, Lisa is a ethically brankrupt scientist, Lola is a future sorority queen, Lana is a dumb redneck, Leni is a special ed kid who probably attends class with Steven Universe. But Luan? Not only is she fucking hideous, she's got some NASTY mental issues that the parents are not only ignoring, but seem to be actively supporting. She video tapes not just her (already a huge red flag) but her brother as well, just in "case" one of them utters a joke in the middle of the night, which screams that she's dangerously obsessive.
That's just fucking weird. Then there's her obsession with pranks on her siblings, which suggests to me that she's lonely and miserable as her stalkish and general shitty behavior has probably made her fellow school students avoid her. Thus she relies on her family for social validation which probably isn't a good sign in a period where a teenager is supposed to grow more and more independent away from the family household. With all this in mind, even a dumbshit like Steven or a total bro like Ed would be hard pressed to be anywhere near her.
Honestly, Lucy is the only one with a sense of moral decency in the whole house.