I don't think so.
Dark Magic does not corrupt
Using Dark Magic does not supernaturally lead to using more Dark magic, or engaging in other evil actions. Harry uses the Imperius Curse twice in Deathly Hallows, and the Cruciatus Curse once. McGonagall also employs the Imperius Curse. Neither of them shows any temptation toward evil, nor do they start escalating their malicious actions thereafter. On the contrary, Harry arguably grows more noble.
Doing Dark Magic does not require being evil
Harry, McGonagall, and various others employ curses or hexes at various points, as mentioned in the previous answer.
Dark Magic does not come from a source of evil
There's no supernatural entity granting wizards their magic, whether benign or malign. So far as the series shows us, anyway, wizarding power comes from some innate quality (as does the magical power of other magical species, which many witches and wizards would rather pretend didn't exist). There's no Morgoth to grant knowledge of necromancy, no Satan to beg for charms.
These are really the three main ways in which something might be said to be "supernaturally" evil, and the Dark Arts fit none of them.
That said, while there may be no metaphysical component to Dark Magic, there is good reason to classify many such spells as evil, particularly thinking from the point of view of someone in peacetime.
Dark Magic is nonetheless unethical
Dark Magic is a rather broad field. Many spells are considered Dark, not merely
the Unforgivable Curses. We can see good reason for many of them:
- The only purpose of the Avada Kedavra curse is to kill. When you have many other spells that can subdue people, using a spell that can only kill them is somewhat evil.
- Crucio does nothing but cause someone pain. Again, there is little use for this spell (in-universe) besides torture, which is a pretty evil thing to do.
- The Imperius Curse removes someone's free will, which many people would consider quite an unethical thing in itself.
- Similarly, Sectumsempra is a particularly painful way of killing someone.
Note that none of these is inherently evil; if Stupefy etc. did not exist, and Avada Kedavra was the only way to stop someone, it might not be wrong. But under the circumstances that prevail for most of the Harry Potter series, the main reasons to use these spells would be negative ones.
More minor types of Dark Magic exist as well. According to JKR:
[Hex h]as a connotation of dark magic, as do jinxes, but of a minor sort. I
see 'hex' as slightly worse. I usually use 'jinx' for spells whose
effects are irritating but amusing.
The key is that such spells are harmful. Also, these minor types of Dark Magic, or at least things "affiliated with" Dark Magic, appear to be taught in school. There's not any particular reason to think that Stunning Spells aren't technically a type of hex, and thus strictly speaking Dark Magic.
Note: Despite this, I would argue that a supernatural morality unconnected to magic itself does exist in the Potterverse. Magic may not be supernaturally evil, but evil is. For example, murder is known to split the soul, and there is no reason to think this works differently for non-magical individuals as for witches or wizards. Love is a powerful force that can be magically harnessed. Nonetheless, "Dark Magic" is a human label.