I am not here to make anyone change ideas nor to deny that Sansa IS one of the most mischaracterized character, and so are her bonds with other characters, but bruh there is absolutely NOTHING in those books that support the idea that Sansa would perceive Elia negatively.
Let's say Elia would actually match the orientalistic negative stereotype of "the typical hypersexual woman" as Ellaria Sand does :
As they were crossing the yard, Prince Oberyn of Dorne fell in beside them, his black-haired paramour on his arm. Sansa glanced at the woman curiously. She was baseborn and unwed, and had borne two bastard daughters for the prince, but she did not fear to look even the queen in the eye. Shae had told her that this Ellaria worshiped some Lysene love goddess. "She was almost a whore when he found her, m'lady," her maid confided, "and now she's near a princess."
Sansa had never been this close to the Dornishwoman before.
She is not truly beautiful, she thought, but something about her draws the eye.
"I once had the great good fortune to see the Citadel's copy of Lives of Four Kings," Prince Oberyn was telling her lord husband.
(A Storm of Swords - Sansa IV)
Sansa not only did not even think anything negative about Ellaria or Oberyn or their etnich/cultural background while being with them, but she even shows admiration for Ellaria Sand.
Ellaria was presented to her as a baseborn woman who raised her power by acting in a way that was considered EXTREMELY scandalous for any decent (not good just decent) Westerosi woman, yet all Sansa cant comment on it - is that Ellaria attract all her attention for be so fierce to look at the queen herself into her eyes.
Shae actively whispered disgraceful words about Ellaria into Sansa's ears, that Ellaria is a whore from Dorne that praise Gods that were actively looked down on by Weserosi and that conquered her power by open her legs, and yet all Sansa could think of - is that she was attracted/mesmerized by Ellaria's power, charme and security.
Ellaria is not just a woman from Dorne but the exact negative stereotype Westerosi had on Dorne and Sansa was attracted by her.
Sure, you can say that Ellaria is still not a noble lady even if she had almost the same power of a princess being prince Oberyn's favorite , yet MYRANDA ROYCE IS A LADY and Sansa is fully aware of her sexual past and position and Sansa still couldn't care less.
The Gates of the Moon was much larger than the Eyrie, and livelierĀ asĀ well. Lord Nestor Royce seemed gruff and stern, but his daughterĀ MyrandaĀ kept his castle for him, and everyone said how frolicsome she was.Ā
(A Storm of Swords - Sansa VII)
"As you say, my lady." Alayne remembered Petyr's warning.
"Randa. Come now, you can say it. Ran. Da."
"Randa."
"Much better. I fear I must apologize to you. You will think me a dreadful slut, I know, but I bedded that pretty boy Marillion."
(A Feast for Crows - Alayne II)
she does not seems to judge Myranda based on her sexual life:
For just a little while, as she ran, she forget who she was, and where, and found herself remembering bright cold days at Winterfell, when she would race through Winterfell with her friend Jeyne Poole, with Arya running after them trying to keep up.
ByĀ theĀ timeĀ theyĀ arrivedĀ atĀ theĀ gatehouse,Ā bothĀ ofĀ them were red-faced and panting. Myranda had lost her cloak somewhere alongĀ theĀ way.Ā
(The Winds of Winter - Alayne I)
Also : where ever Sansa said or thought that a woman couldn't inherit property? Her entire Vale's arc is born due to LittleFinger's belive that she is the only Stark alive and therefore the one that will inherit it. Sansa not only does not say to him that is impossible but resent her claim because she constantly get used for it.
It is not me she wants her son to marry, it isĀ myĀ claim.Ā
(A Storm of Swords - Sansa VI)
Myranda and Ellaria are way more openly sexual and they do challeng the norm way more than woman that would be described in this term by Barristan Selmy would never :
"Princess Elia was aĀ goodĀ woman, Your Grace.
She was kind and clever, with a gentle heart and aĀ sweetĀ wit."
(A Dance with Dragons - Daenerys IV)
so why should Sansa use slur against Elia or call her a slut for her Dornish upbringing when she saw Ellaria being 100 times nearer to that stereotype and did not?
why should Sansa think bad of a woamn that inherit when she herself was used and abused for the possibility of inherit ?