Take a story's temperature by studying its tone. Is it hopeful? Cynical? Snarky? Playful?
The Bacchae is amazing in that for all tragic woe it presents, it's still got tons of laughs. Old Cadmus and Tiresias doing a clumsy jig, the beguiled King Pentheus prancing around in women's clothes – all this in a play with ritual dismemberment and a mother parading through town with her own son's head in her hand. The blending of comic and tragic is an amazing innovation by Euripides. He really was a true dramatic pioneer.