I guess I would say I like words to be articulate--say what they have to say clearly and with a bit of originality; see "Hot Buttered Rum" from the fall songs thread. Traditional lyrics should at least be coherent; some of them sound so pieced together the song doesn't even make sense.

Instrumental tunes need to be distinctive and have some energy, and preferably not too busy or full of key changes or accidentals so I can play them on mountain dulcimer until I learn a better melody instrument! "Elzic's Farewell", "Greasy Coat", "Booth Shot Lincoln", "Flowers of Edinburgh", "Tater Roll", and "Cherokee Shuffle" come to mind.