If you want to have a look at this PDF or ebook, Chapter 4, the "Character of the Early Buddhist Texts" starts on page 66 and ends on page 98. The Authenticity of the Early Buddhist Texts... less than 1Mb... https://ocbs.org/wp-content/uploads/201 ... ticity.pdf
AN 8.53 wrote:Gotami, the qualities of which you may know, 'These qualities lead to passion, not to dispassion; to being fettered, not to being unfettered; to accumulating, not to shedding; to self-aggrandizement, not to modesty; to discontent, not to contentment; to entanglement, not to seclusion; to laziness, not to aroused persistence; to being burdensome, not to being unburdensome': You may categorically hold, 'This is not the Dhamma, this is not the Vinaya, this is not the Teacher's instruction."
I think that would depend on the individual and the structure of his knowledge. It boils down to what we deem as "reliable".
Some would use a historical approach, trying to verify if the sutta was spoken by the historical Buddha or if it is a later addition. Using this approach, some suttas are deemed fake when the language/terms used in it is compared to other/less controversial suttas.
Those who rely on personal experience would try to interpret suttas based on how it correlates with their daily life especially in relation to suffering. Those who follow this approach do not necessarily think of it as fake or geniune, but tend to interpret certain suttas metaphorically, or think of it as a particular teaching to a particular person and should not be generalized.
A third group which is similar to the second group do not feel that i have to accept or reject the whole teaching. Whatever feels relevant and useful they take, and whatever they feel irrelevant and not useful, they suspend judgement.
And the Blessed One addressed the bhikkhus, saying: "Behold now, bhikkhus, I exhort you: All compounded things are subject to vanish. Strive with earnestness!"