It's not a printed rule anywhere that the alignment descriptors on a spell in any way affect your alignment. At best, that's a DM's houseruling decision.
The only spells that mechanically require a specific alignment to use and that could affect your alignment when using them are Exalted & Vile spells. But then not really because you already have to be Good or Evil to cast an Exalted or Vile spell. /shrugs
Edit: The only time the alignment descriptors are brought up in regards to spellcasting is to detail that clerics cannot cast spells with an alignment descriptor that is opposed to his deity's. So a Good cleric could never cast an Evil spell until he does something else to become Evil first anyways. And then it's a moot point