Half-orcs? Redeemable?

[Tuor in Gondolin]

JRRT speculates (apparently negatively in Letters) on the
redemption from evil of orcs, but even if so, there are problems.
In several places there are typical Tolkien half-allusions and/or
hints of orc/humans.
1) In LOTR Frodo says about the Dunlending in Bill Ferny's home:

He looks more than half like a goblin

2) In UT in "The Hunt For The Ring"

Some while ago one of Saruman's most trusted ervants (yet
a ruffianly fellow, an outlaw driven from Dunland, where many said
that he had Orc-blood

Further, if you assume the theory that orcs are elvish in origin,
then these "half-orcs" are both part elvish and part mannish (human)
and so, even if orcs are unredeemable (from the dark side? )
what of these partial orc/elf/man creatures?

And, (by the by) what does it say of Dunlending society's complexity?
They were driven from Rohan and have a respectable grudge with
the Rohirrim, and apparently don't even like, in
principle, even half-orcsees.

[Legate of Amon Lanc]

Interesting thread! But to start even more "liberally", it could be that the Orcs don't come from the Elves at all; and technically, even if they do, I doubt we can say that they have "Elf-blood" anymore - they have Orc-blood now. But we cannot deny, and that's true, that there are half-orcs and that they have at least partially human blood. Now where would they count? Where would they come after their death? Will, let's say, that squint-eyed ill-favoured fellow go before Ilúvatar after his death? I'm not sure how it works with the normal Orcs - I presume they belong in the same category as Elves, and they'll be judged by the "Powers of Arda". Where is then the judgement of the half-orcs?
But concerning the redemption, maybe the half-orcs are irredeemable implicitely, because the deed of crossing the races of Orcs and Men itself is something that, for example, Treebeard defined as "black evil". This could be interpretated the way that such a deed is really something very evil in its very basis. Of course Treebeard is not a voice of the greatest authority, but one may wonder why he calls such a deed "black evil" with apparent disgust. It occured to me that this deed could be something that mirrors the act of connecting the Children of Ilúvatar, the Elves and Men (like Beren and Lúthien), but in the twisted shape, as Morgoth always did with everything. So if Saruman commited such a deed, and it could be interpretated this way, I would surely say together with Treebeard: "Now that would be black evil!" The union of Elves and Men, blessed by the union of the children of Beren and Lúthien, is stained by the wretched union of Orcs and Men. What do you say?

And, (by the by) what does it say of Dunlending society's complexity?
They were driven from Rohan and have a respectable grudge with
the Rohirrim, and apparently don't even like, in
principle, even half-orcsees.

I believe that the fact that the "normal" Dunlanders did not like the "orcy" ones is just pure, well, racism... or more likely, just a subconscious usage of the general knowledge that the Orcs are something evil in Middle-Earth. Who would like to befriend with something like that? Even the Men under Morgoth (or later Sauron, probably) were not much close to the Orcs who fought alongside them. And vice versa.

[Thinlómien]

This doesn't have very much to do with the topic of this thread, but as you might be interested in this as well and it speculates on otc's nature (are they evil), you might want to have a look at this.

Orcseys - always evil?