First, I want to say that this seems to me a deep question for which I have rather slender qualification. I usually respond to more technical questions that don't involve introspection or contemplation of human nature. However your question didn't get very many responses here, and after I thought about it for a few days I began to feel that I had something to offer, even if something ultimately inadequate.
I'd like to start by considering the general attitude of Chazal toward temptations.
Rav Ashi wondered about the fact that even great people in earlier times succumbed to a temptation that he easily resisted, a temptation to worship idols. When occasion somehow presented itself he communicated with the spirit of Menashe King of Yehudah, who had lived and died 25 generations earlier (in the times of Hosea, Amos, Isaiah and Micah), when the desire to worship idols was strong. Rav Ashi expressed wonderment that even great men of early times wished to worship idols. Menashe responded that if Ashi had lived during earlier times he would have lifted the hem of his skirt to run to the idols. See Sanhedrin 102b1; 2 Kings 15:16 to 22; and the Judaica Press introduction to 2 Kings.
What is this story doing in Shas? Why is it helpful for us to know about Rav Ashi and King Menashe? Perhaps in this story Chazal ask us to bear in mind that when people face challenges, it is not easy for us to know whether those challenges are difficult for them; and this is especially true when our vantage is from a great distance.
Elsewhere in Shas, Abaye overheard a man and a woman planning a journey. He followed them, expecting to intervene if they came to sin. But they traveled together and then parted ways, saying, "Our paths diverge now, but the company would have been pleasant." Abaye became despondent, reflecting that he would himself have been overcome by temptation, until he learned that whoever is greater than his fellow has a greater temptation than his fellow. See Succah 52a3.
Would you say that Abaye was dissembling when he said that he would have been overcome by temptation? Whom was he trying to fool, and why? The gemara tells us directly that he was despondent because he would have failed. See also Shemonah Perakim 6 (of the Rambam); Akeidas Yitzchak, Parshas Nitzavim p. 104b ff; Or Yisrael 30.
Similarly the story you quote, from Avois d'Rabbi Nosson, seems to ask to be taken at face value. While I agree that we should consider whether people in the Talmud are always candid, I see here no reason for misstatement; there is nothing to gain by it.
Further, if the redactor had thought that R' Akiva's statement was not candid, there would seem to be no reason to include the story at all. The context seems to require it. First, AR"N quotes a statement of Pirkei Avois: the evil inclination drives a man from the world. A series of reflections on the evil inclination, on the difficulty of overcoming, leads to the tale of Joseph the righteous; then to Zadok the greatest man of his generation; then to R' Akiva, who was greater than he; and then to R' Eliezer the great, who was more distinguished than he. Each rebuffed sexual overtures. Then there follow several more paragraphs on the fearsomeness of the evil inclination. If the point is not that these men were genuinely tempted, then what is the point?
(Incidentally the stories also contain ingredients that seem to make sin more bizarre. One involves a little girl who is the rabbi's sister's child; I would consider this an almost uniquely non-tempting situation. And yet the stories praise this degree of self-control.)
R' Akiva's explanation involves the stench of carcasses. The only reason he refrained from disgraceful behavior is some detail that seems beside the point. What should our attitude be? Should we be disappointed in him for being a man of a certain nature? Or should we (perhaps like him) be glad for any contingency that helps us remain true to our goals? This whole world is a very narrow bridge, and the whole point of view of the story is that R' Akiva's level of self-control is remarkable. The jailer apparently sends women in to visit prisoners routinely because the need is widespread; he is as surprised as the women themselves when R' Akiva refuses this offer. For ourselves, we commonly manipulate circumstances (to make our own failure less likely) simply by avoiding seclusion and remaining in public view. I believe that this works, and if someone told me that the only reason he did not sin was that he would have been embarrassed to be seen sinning, I would say that he is no weaker than others, just more honest. So I would not dismiss a moral victory that is contingent. They're almost all contingent; but is this one really so small?
P.S. Some say that Yochanon Kohen Gadol was later called Yannai. See Berachos 29a1.