In your opinion, which attributes are most condemned in Tolkien's works?

TL;DR : I believe treachery and possessiveness are the two most condemned traits in Professor Tolkien's works.

So far, I've only read The Lord of the Rings trilogy, The Hobbit, and I'm halfway through The Silmarillion. I believe there are certain traits that are strongly condemned in Professor Tolkien's viewpoint.

I believe the first and boldest of these traits is treachery. In The Fellowship of the Ring, at the council of Elrond, where the treachery of Saruman is ultimately revealed, we gradually see how significantly it impacts the fate of the people of Middle-earth. However, Saruman paid dearly for betraying the White Council. I assume that among the condemned traits and attributes, treachery and betrayal are the most sinister deeds in Tolkien's worldview.

Next to treachery and betrayal, I believe, stands possessiveness. In The Silmarillion, possessiveness is especially one of the central themes concerning Fëanor and his seven sons. At first, I confused it with greed, but they imply slightly different meanings, at least in my humble opinion, and they seem to have a very close relationship. Many things might lead someone to be a possessive person, and greed is one of them. That said, greedy people are potentially prone to possessiveness. Dwarves are known to be a greedy race, but Fëanor and his household are known for their possessiveness of the Silmarils. They swore an oath that obliged them to claim the Silmarils only for themselves, and they had to fulfill it.

While greed and possessiveness are not identical, there are certainly other traits and attributes that have been criticized by Professor Tolkien, such as lying and fear, but these two appear to have received the most focus, and the Professor has elaborately reflected on them.