Match Emotion of Lyrics with Music

[MasterChief]

What are some important things to consider while matching the emotions of the lyrics with music?

Scary lyrics = scary music
Dreamlike lyrics = dreamlike music
Sad lyrics = sad music
Happy lyrics = happy music
Etc.

My guess is that scales are very important for doing this, but I'm afraid I don't have much knowledge about scales.

[floydbass]

What key the songs is in has a bearing on this, certain keys are sadder(minor) than others(major)

[JimK]

Sometimes a 'happy-sounding' tune with ominous lyrics works-
The Beatles' "She Said She Said" or "Maxwell's Silver Hammer".

To answer your other comment about "guessing scales are important"-
If a mode with a b5 or a b2 is used...a certain vibe may be felt just from that.