" ' The person, be it gentleman or lady, who has not pleasure in a good novel, must be intolerably stupid. I have read all Mrs Radcliffe's works, and most of them with great pleasure. The Mysteries of Udolpho, when I had once begun it, I could not lay it down- I remember finishing it in two days-my hair standing on end the whole time.' "
'Yes', added Miss Tilney, 'and I remember that you undertook to read it aloud to me, and that when I was called away..., you took the volume into the Hermitage Walk, and I was obliged to stay till you had finished it'. (ch. 14)

I still feel it is too simple to state 'NA is a mockery of Gothic books.'
JA read many Gothic novels for entertainment. (She also sent a copy of 'Emma' to a favourite Gothic author, Maria Edgeworth.)
My impression is JA thought readers of novels should be allowed to enjoy them rather than be censured- as she ably set out earlier in Ch. 5 The defence of the novel-
'no species of composition has been so much decried. From pride, ignorance, or fashion, our foes are almost as many as our readers. And while the abilities of the nine-hundredth abridger of the History of England, or of the man who collects nd publishes in a volume some dozen lines of Milton, Pope or Prior, with a paper from the Spectator,...,- there seems almost a general wish of decrying the capacity and undervaluing the labour of the novelist,'
Perhaps a combination of truth and irony.

We know Henry and Eleanor Tilney read and enjoyed Gothic books and they are well educated and versatile readers. Yet unlike Catherine or esp. Isabella they do not seek to impose ideas from novels on daily life so I doubt JA is parodies them as readers.
JA is more concerned with how a reader may judge a book. Or, as we see in Ch. 5 how a History is written or a Compilation of poetry. Often, the same writers who decry novels abridge history with few dates, or compile a miscellaneous collection of poems while slighting novels- 'I seldom look into novels'.

Many readers do mistake fantasy for reality- these are the readers I feel JA essentially parodies in NA. Isabella Thorpe reads out a jumble of titles, sent to her by a Miss Andrews of new Gothic titles- Clermont, Castle of Wolfenbach, Midnight Bell, etc. She truly personifies the non-discerning reader who only likes escapism in her everyday life--balls, quizzes, flirtations and in her reading of the latest novels.
Thus, she is a bad influence on the imaginative still inexperienced Catherine.
I doubt JA means readers have to be well educated or even 'highly discerning' to understand gothics, but simply excercise a degree of commonsense as one should do with all reading matter.
Readers like the Tilneys may read Gothics for amusement. They also read history, Gilpin. Catherine also reads poetry and plays. Yet Isabella never varies her reading habits and she never shows much judgement. What of John Thorpe with his bawdy enjoyment of 'The Monk' ? More likely John wants lurid thrills, not merely reading for amusement. I think John is also a parody of excesses. He presents a contrast to Henry Tilney and is gross, boorish- and fantasizes Catherine is an heiress.

Essentially, I can agree. NA is a parody of not only Gothic novels but more importantly, of those readers who do not excercise judgement so tend to mistake fantasy for reality.
It is how one judges and reads a novel which I think JA is most concerned with. Why would she condemn a literary genre she enjoyed reading ? At this point, it does not make sense to me the hero and his sister read Udolpho if JA condemns this novel by a sister author.

Whatever happens next, I'm sure the suspense is killing me...

* I enjoyed these passages of Emily in the ruined chapel Udolpho, Ch. 17.

They reminded me of Catherine's thoughts about Northanger Abbey of last paragraph NA, Ch. 17

[on Miss Tilney's answers] 'she was hardly more assured than before, of Northanger Abbey, ..., of it's having fallen into the hands of an ancestor of the Tilneys at the time on it's dissolution, of a large portion of an ancient building still making a part of the present dwelling, although the rest was decayed,'