Formal:
* He cast a disdainful glance at the cheap trinkets on display.
* The professor regarded the student's simplistic argument with disdainful amusement.
* Her disdainful tone made it clear she had no interest in our conversation.
Informal:
* She rolled her eyes, a disdainful smirk playing on her lips.
* He dismissed their concerns with a disdainful wave of his hand.
* The teenager looked at his parents with disdainful indifference.
Literary:
* The queen's disdainful gaze swept over the kneeling peasant.
* The artist's disdainful brushstrokes captured the subject's arrogance.
* The villain's disdainful laughter echoed through the chamber.
Note: "Disdainful" usually implies a sense of superiority or disgust. The tone of the sentence will usually be negative, showing a lack of respect or interest.