I like many kinds of music but I do judge in quite hard. Their are several things however that set off my shitiness alarm.
-Cookie cutter whiny lyrics. See Dashboard Confessionals
-Bending syllable sounds to make them rime. See Blink 182
-Rap songs without any sort on complicated music or rythym. I'd give an example but I fear I would list have the rap music industry.
Their are a few others but they escape me at the moment.
So, stuff I like
-Speed, Machinae Supremacy
-Complex lyrics, Poets of the Fall
-Classical Influence, Sonata Arctica
-Interesting use of electronic instruments, The Protomen
-Progressive, Emerson, Lake, and Palmer
-Late ninety's alternative, Fuel
Bands I found because of Pandora.
On Poets of the Fall radio,
Sunrise Ave., Withing Temptation, Adema, The Rasmus, Daugherty, Rpwl, Storyside B, Kent.
On The Protomen radio,
Iron Savior, Symforce, Dozer, Excalion, Black lab.
On Nightwish radio,
Within Temptation (again), Lacuna Coil, A Wish for Fire, Theater of Tragedy.