Nietzsche indeed enacts a 'transmutation of all values', yet not to elevate the value of evil.
Rather, it is a matter of transcending the dichotomy of good and evil, rising 'beyond good and evil'. He ascribes no inherent meaning to these two concepts beyond being symptoms of a certain physiological constitution. For Nietzsche, rejecting morality is not about choosing evil over good; anyone who does so remains ensnared in the moral framework that upholds the opposition between good and evil. Such a person is still confined by moral constructs.
The superhuman is one who surpasses this framework, embracing neither side of the moral dichotomy but existing 'elsewhere'; he is not 'immoral' but 'a-moral'.

Sade, on the other hand, appears closer to the notion of immorality that we seek to examine. The audacious lines of Sade's works and the seductive danger radiating from Philosophy in the bedroom have long consigned his writings to the hidden shelves of libraries. Here, we seem nearest to an axiological stance that assigns supreme value to evil. However, Sade, perhaps with deliberate mischief, chooses instead to advocate the opposite view. While Sade exalts destruction and cruelty, he does so not to glorify crime but rather to deny that such acts are crimes at all: Destruction being one of the chief laws of Nature, nothing that destroys can be criminal; how might an action which so well serves Nature ever be outrageous to her? ¹.

In his rhetorical manoeuvring, Sade does not question the value of virtue itself, but rather redefines the essence of virtue; true virtue, he claims, lies in cruelty, not pity: Cruelty, very far from being a vice, is the first sentiment Nature injects in us all. Cruelty is simply the energy in a man civilization has not yet altogether corrupted: therefore it is a virtue, not a vice ².

Further, in condemning human pride much like a Church Father, Sade astonishingly concludes that murder is legitimate! Indeed, Tis our pride prompts us to elevate murder into crime. Esteeming ourselves the foremost of the universe's creatures, we have stupidly imagined that every hurt this sublime creature endures must perforce be an enormity; we have believed Nature would perish should our marvelous species chance to be blotted out of existence ³.

Moreover, Sade upholds the foundational framework of morality by adhering to a legitimising principle—not God, but Nature. For example, Sade notes that Women are not made for one single man; 'tis for men at large Nature created them, and he urges them as follows: Listening only to this sacred voice, let them surrender themselves, indifferently, to all who want them ⁴.
Evil, therefore, is not self-justifying; it is not embraced for its own sake. Instead, Nature serves to legitimise evil, just as God once legitimised good. This legitimisation effectively reclassifies evil as good rather than evil. The object of affection is not evil itself but Nature, which one pursues through acts deemed evil. Here, Sade does not engage in evil because it is evil but because it is natural.

Ultimately, rather than affirming the value of evil, Sade seems to make it vanish, similar to classical theodicies. For instance, Eugénie exclaims in response to Dolmancé's endorsement of incest: Oh! My divine teachers, I see full well that, according to your doctrine, there are very few crimes in the world, and that we may peacefully follow the bent of all our desires, however singular they may appear to fools ⁵.
To which Dolmancé replies: There is crime in nothing, dear girl, regardless of what it be: the most monstrous of deeds has, does it not, an auspicious aspect? […] Well, as of this moment, it loses every aspect of crime; for, in order that what serves one by harming another be a crime, one should first have to demonstrate that the injured person is more important, more precious to Nature than the person who performs the injury and serves her; now, all individuals being of uniform importance in her eyes, 'tis impossible that she have a predilection for some one among them; hence, the deed that serves one person by causing suffering to another is of perfect indifference to Nature ⁶.

Sade, therefore, appears to deny the existence of evil rather than to glorify it. Behaviours valued—such as cruelty and debauchery—are redefined not as evil or vice but as virtue, properly understood.

However, we might question whether Sade should be taken seriously as a thinker and if his texts, which may have been intended to mock serious moral discourse, merit earnest analysis. We should be careful not to misinterpret irony as a consistent doctrine.

These ideas are specific to Philosophy in the Bedroom, whereas in The 120 Days of Sodom, characters embrace evil for its own sake, recognising it as vice rather than misunderstood virtue. Here, the pleasure derived from evil is held as the supreme value: [These principles] have made me understand the emptiness and nullity of virtue; I hate virtue, and never will I be seen resorting to it. They have persuaded me that through vice alone is man capable of experiencing this moral and physical vibration which is the source of the most delicious voluptuousness; so I give myself over to vice ⁷.
However, it should again be noted that nature serves as the legitimising principle: These instincts were given me by Nature, and it would be to irritate her were I to resist them; if she gave me bad ones, that is because they were necessary to her designs ⁸.

In conclusion, it bears repeating that extreme axiological positions are rare in literature or philosophy. This holds true for the love of evil for its own sake, or 'radical evil', as it does for nihilism and eclecticism. Rather than discrediting these doctrines, this rarity underscores their truly extraordinary nature.

1. Philosophy in the bedroom, p. 433
2. Ibid., p.449
3. Ibid., p.434
4. Ibid., p. 481
5. Ibid., p. 433
6. Ibid., p.478
7. The 120 Days of Sodom, p.26
8. Ibid., p.27