1. Strong beat, ideally syncopated; and/or epic-sounding (e.g. film soundtracks, madrigals).
2. Relatively melodic singing.
3. Unique chords, and/or unique chord progression, and/or amusing lyrics, and/or unique instrumentation.
4. Minimal noise (cymbals, guitar wash), should have a clean sound.
5. No falsetto, unless you're black or Beck. Deeper = better, regardless of gender.
6. No yelling/screaming.
7. Not repetitive.
8. Bonus: slide guitar.