[Scott]

Morwen,
I don't think that it's an issue of being tainted as much as it is just having to look at who was after the the silmarils and the trees and why.
Morgoth and all of his legions went after the trees to pursue them because it was a work of the "good guys" and he being a bad guy meant that he was sworn by the bad guy oath to defile it. He pursued the trees not because they were tainted, but because they were pure.
I think this is also true with the silmarils. Morgoth absolutely hated the elves and all other children of Iluvatar and any of their creations. The idea of an elf, Morgoth's "enemy", having created something so beautiful and perfect meant that he either needed to destroy it or let his own greed kick in and hoard it.
The reason the other elves wanted the silmarils was out of sheer greed as well. The only elves who had any real claim for them would've been Feanor's own kin and children. To the other elves, the silmarils were just a chance for a smash and grab operation to own "the best" of something. The elve's love for all things beautiful was certainly one of their downfalls as was Morgoth's contempt for them.
As Tolkien once stated,
"If more of us valued food and cheer and song above hoarded gold, it would be a merrier world."
I think that this was point he was trying to get across here.
~Scott