The following contains spoilers for The Dawn of the Witch Episode 6, "Knowledge of Ignorance," now streaming on Crunchyroll.
Fans of Grimoire of Zero will recall social cluelessness as one of Zero's defining traits as a character and the source of most of the show's humor. Despite being a powerful witch, Zero often lacked basic social decorum and consistently failed to understand why her friends Mercenary and Albus found her behavior embarrassing. Zero herself also failed to understand human values and especially the human concept of modesty.
Amongst Zero's greatest hits when it comes to social situations is the time she stripped naked in a clothing store in front of everyone while trying on new clothes, not understanding why Mercenary quickly threw her into a changing room. She followed up on this when she later asked Mercenary why he had no issue showing his private parts during a bath. She also embarrassed Mercenary when she passed herself and Albus as his sex slaves as a way of gaining quick entry into a new town, not understanding why he hit both of them on the head. There's also the iconic moment where Zero and her brother Thirteen ceased battling with each other just because it was dinner time, leaving Albus and Mercenary dumbfounded.
In The Dawn of the Witch, Zero appears to have learned some basic social skills since her earlier days. However, she still fails to understand certain things like why Loux Krystas thinks it's bad for her nephew Saybil to stagnate on his magical prowess. Instead of seeing it as a potential problem, she instead sees it as him learning at a different pace from his classmates Hort and Kudo. Interestingly, Zero's most endearing trait has been passed on to her nephew -- as Loux Krystas learned the hard way.
In the two months that Saybil has been residing with his aunt in his new town, he opened up a magic shop, supplying magic to all who need it. One of his recurring customers is his classmate Hort, who experiences feelings similar to an orgasm whenever he touches her and imbues her with his magic powers. Like his aunt Zero, Saybil doesn't catch on to the fact she's sexually attracted to him and only asks him to "supply" her with magic just so she can get her sexual fix. This is no different from the time Zero had no clue what a kiss was when she caught a couple kissing on the street in Grimoire of Zero, with Mercenary having to explain it as a gesture of love. The only difference is that Saybil doesn't try to find out what sexual pleasure feels like the same way that Zero tried to experiment with kissing.
As frustrating as it is for Loux Krystas to process Saybil's inability to recognize Hort's sexual interest in him, this proves to be the least of her worries. When she learns the details of why he never leaves his shop, she's even more mortified by his lack of social decorum. During a conversation about what he does throughout his day, Saybil discloses that apart from supplying people with magic, he cleans the house and washes his friends' clothes, including Hort's. The detail that alarms Loux is finding out that Hort purposely leaves out her dirty underwear for Saybil to find. Of course, Saybil fails to see the problem.
From Saybil's point of view, there is no harm in doing laundry. All it is for him is taking dirty clothes and washing them with water and soap. From Loux's point of view, a boy washing a girl's underwear has more intimate implications than just "washing dirty clothes." To start with, Loux is not oblivious to Hort's romantic interest in Saybil and is clearly taking advantage of his naïveté to make sexual advances toward him. The other thing that's not escaping Loux is that if Saybil was to take Hort to the middle of the woods and say "you're cute," Hort would undoubtedly attempt to have sex with him on the spot and "make him a man" overnight.
To Loux's frustration, Saybil understands her phrasing to mean that Hort will cast some kind of magic spell that will turn him into an old man if he tells her she's cute. To try and get him to understand the problem, Loux tries to get him to consider it from a different perspective: how would he personally feel if a hairy-looking dude sniffed his underwear while doing laundry? Once again, Saybil interprets this to mean that Hort pictures him as the hairy-looking man from Loux's scenario when doing her laundry.
After a while of trying to get Saybil to "get it," Loux inevitably gives up, especially when she remembers her last conversation with Zero. Prior to Saybil attending Albus' Magic Academy in Wenias, Saybil had erased his own memories as a form of punishment for witnessing his mother's murder. While it may be easy to argue that Saybil's social cluelessness is genetically linked considering his aunt is the same way, at the same time, it may actually be the result of his memory wipe since he appears to be a more extreme case than his aunt.