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.