Here’s a mashup that re-contextualizes scenes from Ferris Bueller’s Day Off by combining them with the score from Requiem for a Dream:

This demonstrates how strongly music affects mood and how we perceive scenes synced with a score.
In the Star-Ledger, Alan Sepinwall interviews the composers for Lost and Battlestar Galactica: Michael Giacchino and Bear McCreary, score keepers: “The trend in television music of late has been towards wall-to-wall songs, like on “Grey’s Anatomy.” But a handful of series still use traditional scores, and some composers – notably Giacchino on “Lost” and Bear McCreary on “Battlestar Galactica” – have been able to do transcendent work in an area that’s too often underappreciated. On most TV shows, the music is the most important dramatic element that you notice the least. With “Lost” and “Battlestar,” it’s impossible not to notice, or to think of either series without some composition or other by Giacchino or McCreary coming into your head.”
And here are Sepinwall’s transcripts of the interviews with Giacchino and McCreary.