Beauty lies in the eye of the beholder. Your perception of the external world reflects your view of yourself. What you see as beautiful or ugly is actually how you see yourself. Its not about the flower.its about you. Because what you use in seeing are your eyes.
The flower is as it is. It doesn't change despite your criticism or praise. But the who changes is you..your internal state. You'll feel negativity if you say something negative..it's the reality you've created.
That's why they say, if there's nothing good you can say, remain silent. Protect yourself from giving out negative energy. What you give out comes back to you.