Do spell casters know how long their spells are active, and can they tell at a glance?
Specifically lets talk about blindness/deafness, as I know its a permanent duration and dismissable. Does the spell caster who put someone under this spell know how long it is active? Could they tell automatically just by seeing the person (without any clues like them walking in a maze without difficulty or reacting to a sound)? So could they tell if someone has broken the spell they cast?
Unless the GM gives casters a greater sense of their own spells than the game says casters have, a caster knows very little about the majority of his spells after they're cast, especially those spells with a duration like instantaneous and permanent. A caster knows if a creature that he's targeted with a spell succeeds on a saving throw against that spell, and, presumably, a caster knows what the duration of his spells should be, but unless the spell itself specifically describes the caster being informed that the spell's been altered, the caster is unaware of any changes that've taken place to what he might still consider his spell (up to and including that spell being dispelled).
However, the subject will be aware when many spells that affect itself disappear (e.g. deathwatch, status), whether naturally because the spells' durations expire or prematurely because the spells're dispelled or suppressed, but in some cases the presence or absence of a spell may be unknown until too late (e.g. a GM may rule that the creature was unaware that its freedom of movement spell was dispelled while the normally-not-paralyzed creature enjoyed a leisurely walk, unaccosted by beggars, down the unflooded, unwebbed city street).
This can leave a caster in the unusual position of wondering if he should take a standard action to dismiss a spell that's already been dismissed. In the case of blindness/deafness specifically, the spell's subject must be within medium range for the caster to dismiss the spell, so the caster could possibly determine if the spell were in place simply by waving something in the affected creature's direction or yelling at the creature rather than potentially wasting a standard action dismissing a spell already removed.
Note: This GM believes casters well-versed in the spells they cast, assuming, for instance, geometry so much a part of caster training that a caster can place area spells on the grid in far less time than the player. Likewise, this GM assumes once a spell that's on a clock is cast, the caster naturally keeps track mentally of the spell's remaining duration; instantaneous and permanent spells, however, in this GM's campaigns, lack such a countdown.
