yes, I think Tolkien is making a general comment on evil. On a trite
level, it's the old adage about thinking you can touch pitch and not be
defiled. Something always rubs off and
sticks.
__________________________________
All that is gold does not glitter,
Not all those who wander are lost;
The old that is strong does not wither,
Deep roots are not reached by the frost.
From the ashes a fire shall be woken,
A light from the shadows shall spring;
Renewed shall be blade that was broken,
The crownless again shall be king.