Oracles and fortune tellers

A house-rule I'm considering for that game I'm eternally planning to run is letting characters consult a fortune teller before leaving on an adventure.  The fortunes would be mostly beneficial to characters, letting them cash in a fortune to gain a one-time mechanical advantage.

But of course it wouldn't be any fun if all the results were advantages, would it?  Characters have to accept the risk that they've consulted a fraud, or the signs were unclear or the oracle didn't think the character's gift was impressive enough to really dig into what the spirits are saying today.

This settlement's oracle is (1d6):

1. A temple sybil, attended by priest-scribes in a high-roofed white room, surrounded by votive fires.
2. A blind madwoman who put out her own eyes to escape the visions, chained to keep her from hurting herself, managed by nurse-guards.
3. A scarred old soldier with a head wound that healed badly, sleeping rough under a bridge and mumbling to himself.
4. A former cleric to a scattered and suppressed cult of a god opposed to one of the characters' gods, living in a slum and selling predictions to earn a living.
5. A foreigner from a despised race, operating a booth in the marketplace and relying on her powers and wits to protect her from the locals' resentment.
6. A senile wizard, diminished in power but still prone to flashes of brilliance and uncannily accurate predictions.

The oracle tells fortunes by (1d6):

1. Drinking ergot mixed with wine and interpreting the visions.
2. Listening to the petitioner describe their dreams and explaining the meaning.
3. Observing the reflections of light on metal.
4. Reading the cards.
5. Staring into a dark glass and watching for portents.
6. Consulting the dead through necromantic ritual.

As payment the oracle asks for (1d6):

1. Gold equal to the price of a sword.
2. A personal item.  Just a trinket, really.  Nothing you'll miss.  Don't worry.
3. A prayer or minor sacrifice on the oracle's behalf.
4. Food, clothing, wine.  The basic necessities.
5. A handshake, a kiss... some kind of personal contact.  No, there's no hidden significance.  Why do you ask?
6. Visit a person the oracle describes and deliver a cryptic message.

In return the petitioner gets (1d10):

1. Character may re-roll one failed save of their choice.
2. False vision.  Character must re-roll one successful save of the GM's choice.
3. At a time of the player's choice the character can pull out the perfect piece of equipment for the situation.  Lose one encumbrance slot until then.
4. Character may retroactively disarm one trap.  Any harm done by it is simply a vision of what would have happened.
5. Incomplete vision. A single danger the character successfully avoids has a second, hidden, danger behind it.
6. The first time the encounter die indicates a wandering monster, the GM informs the player in time to avoid the encounter or gain surprise.
7. The character is made aware of one of the adventure's treasures and the general location it can be found.
8. Tunnel vision.  The character is made aware of one of the adventure's treasures that has a threat linked to it.  There's no mention of the threat.
9. During an encounter of the player's choice, the character is aware of the encountered creature's name.
10. During a hostile encounter of the player's choice, the character knows what tactics the encountered creature will use.

Some of these results would be appropriate to conceal until it's time for them to happen.  Rather than fooling the players, I'd give them something like "all will become clear when the time is right."  These advantages would last until the end of the current adventure.  If not cashed in, well, the fates are ever-changing and man is but a lesser piece on the game table of the gods.