In "Fahrenheit 451", doesn’t Montag have a bad feeling when he destroys books, houses etc. ?
In the beginning, his feelings are quite the opposite of feeling bad about it. He gleans quite a bit of joy from burning. The first sentence of the novel says "It was a pleasure to burn", then goes on to describe how Montag "grinned the fierce grin of all men singed and driven back by flame". He enjoys burning books so much in fact that Bradbury compares it to "the hands of some amazing conductor" and that Montag "strode in a swarm of fireflies", both beautiful instances of imagery to describe something so inherently violent and destructive. At night, "the fiery smile still gripped...his face muscles"; even in sleep, Montag's joy at burning carries over.
Later however, after his eyes are opened a bit, we see his reaction change. When Mrs. Blake refuses to leave the house and is burned along with her books, her staunch defiance, in combination with Montag's fresh perspective on life, leaves him disturbed. He stays home the next day, feverish, sick about it. He realizes that "there must be something in books...to make a woman stay in a burning house...you don't stay for nothing." And, Montag never burns a house again. The pleasure is gone; he recognizes it for the atrocity that it is.