In Fahrenheit 451 what quotations in the book show that technology is bad in their society?

I think any quotations that display the state of Montag and Mildred's relationship are good quotes for your question.  Mildred is addicted to the media technology.  So much so that it has destroyed the relationship between Montag and Mildred.  They simply do not interact as a couple anymore, because Mildred would rather spend time consuming media tech than conversing with her husband.  Not only that though, but the technology actually becomes life threatening to Mildred,...

I think any quotations that display the state of Montag and Mildred's relationship are good quotes for your question.  Mildred is addicted to the media technology.  So much so that it has destroyed the relationship between Montag and Mildred.  They simply do not interact as a couple anymore, because Mildred would rather spend time consuming media tech than conversing with her husband.  Not only that though, but the technology actually becomes life threatening to Mildred, because she simply isn't capable of maintaining a healthy life without her pills.  Her problem is that she can't control the amount that she takes.  The technology is destroying her and her ability to operate on anything close to resembling a decent interpersonal relationship with real people.  The following quote is a bit long, but it shows what a hollow shell Mildred has become.  

Without turning on the light he imagined how this room would look. His wife stretched on the bed, uncovered and cold, like a body displayed on the lid of a tomb, her eyes fixed to the ceiling by invisible threads of steel, immovable. And in her ears the little Seashells, the thimble radios tamped tight, and an electronic ocean of sound, of music and talk and music and talk coming in, coming in on the shore of her unsleeping mind. The room was indeed empty. Every night the waves came in and bore her off on their great tides of sound, floating her, wide-eyed, toward morning. There had been no night in the last two years that Mildred had not swum that sea, had not gladly gone down in it for the third time.

This next quote is along the same lines, but it definitely shows how Mildred's TV watching habits have come between the two of them. 

Well, wasn't there a wall between him and Mildred, when you came down to it? Literally not just one, wall but, so far, three! And expensive, too! And the uncles, the aunts, the cousins, the nieces, the nephews, that lived in those walls, the gibbering pack of tree-apes that said nothing, nothing, nothing and said it loud, loud, loud. He had taken to calling them relatives from the very first. "How's Uncle Louis today?" "Who?" "And Aunt Maude?" The most significant memory he had of Mildred, really, was of a little girl in a forest without trees (how odd!) or rather a little girl lost on a plateau where there used to be trees (you could feel the memory of their shapes all about) sitting in the centre of the "living-room." The living-room; what a good job of labelling that was now. No matter when he came in, the walls were always talking to Mildred.