Elinor's assessment of Lucy is much more sensible and fact-based than you make it out. In full it is:

Lucy was naturally clever; her remarks were often just and amusing; and as a companion for half an hour Elinor frequently found her agreeable; but her powers had received no aid from education, she was ignorant and illiterate, and her deficiency of all mental improvement, her want of information in the most common particulars, could not be concealed from Miss Dashwood, in spite of her constant endeavour to appear to advantage. Elinor saw, and pitied her for, the neglect of abilities which education might have rendered so respectable; but she saw, with less tenderness of feeling, the thorough want of delicacy, of rectitude, and integrity of mind, which her attentions, her assiduities, her flatteries at the Park betrayed; and she could have no lasting satisfaction in the company of a person who joined insincerity with ignorance; whose want of instruction prevented their meeting in conversation on terms of equality, and whose conduct towards others, made every shew of attention and deference towards herself perfectly valueless. (chpt 22).

Elinor has known Lucy for several days at this point - enough to frequently find Lucy agreeable as a companion for half an hour, and consequently enough to determine if Lucy is ignorant or well-read.

Elinor's observation about the "want of delicacy, rectitude and integrity of mind" appears to arise from Lucy's flattery of the Middleton's, and that, unlike Elinor, she seems to feel no tension between the demands of politeness and those of truth:
"What a sweet woman Lady Middleton is," said Lucy Steele.

Marianne was silent; it was impossible for her to say what she did not feel, however trivial the occasion; and upon Elinor, therefore, the whole task of telling lies when politeness required it, always fell. She did her best when thus called on, by speaking of Lady Middleton with more warmth than she felt, though with far less than Miss Lucy. (chpt 20).

Elinor does not find Lucy's attentions to her flattering because Lucy shows the same attentions and flattery to everyone else, which strikes me as fair enough.

You say that you cannot accuse Lucy of being a snoop or a conniver at this stage. But I cannot find any bit where Elinor thinks, says, or implies Lucy is a snoop or a conniver before Lucy has that conversation about Edward Ferrars. Consequently this implies that Elinor is not biased about Lucy - Elinor does not accuse Lucy of something she has no evidence for. Unless that is, you have a quote I've missed of where Elinor thinks such things of Lucy.

Why do you state that Elinor cannot compete in the looks department? I am not aware of any comparison JA or anyone else makes between Elinor and Lucy's beauty. Both are described as pretty (Elinor in chapter 7).