What is the ruling on a person saying, for example, "this color inspires optimism"?

There is no harm in being optimistic about a beautiful color, because it is a good omen that the Prophet, peace and blessings be upon him, admired, and because pessimism is a bad assumption about Allah without a compelling reason, while optimism is a good assumption about Him. Indeed, it has been instilled in people's nature to love good words and righteous omens, to feel comfort in them, and to be at ease with an elegant sight.