StreamOfTheSky
Adventurer
If you know you're fighting a nymph, you're generally going to go with "Averted Vision", simply because Blinding Beauty and Stunning Glance are generally going to be known issues. It may never trigger.
...Did you just completely miss that I was joking, or are you trying to rule -mechanics-analyze what I said despite knowing it was a joke?
As for the rules...rules be damned. If there was a topless nymph, ignoring that only 3 core classes actually have the class skill to ID her and know "looking = bad" anyway, I wouldn't be roleplaying most of my characters properly if I chose to have them avert their eyes...