I made a few corrections and additions to sjohnston's excellent potion identification flow chart, and added a section on scrolls.
I also included some guidance for prices that shopkeepers offer to you.
Follow the step presented, in order, until your item is identified.
Potions
* Is it "clear"? WATER
* Did you get the potion from a nymph? : (probably) OBJECT DETECTION
* (a)pply the potion.
<Lights> : OIL ((a)pply again to unlight)
* #dip an unneeded tool "(" into the potion.
<transforms into another tool> : POLYMORPH (Uses up the potion)
* #dip a non-poisoned missile weapon into the potion
(in case you have no unicorn horn, or want poisoned weapons)
<Coats weapon>: SICKNESS (Uses up the potion)
* #dip a unicorn horn into the potion
<Turns clear>: was HALLUCINATION, CONFUSION, or BLINDNESS; now WATER
<Color changes>: was SICKNESS, now FRUIT JUICE
* #dip amethyst (or violet gems that might be amethyst) into the potion
<Changes color>: was BOOZE; now FRUIT JUICE; (gem is AMETHYST)
* (d)rop the potion in a shop.
Offer price<A,B/C,D>[base price] POTION TYPE(s)
-----------------------------------------------
< 2, 2 / 1, 1>[5] UNCURSED WATER
< 25, 19 / 16, 12>[50] SEE INVISIBLE, BOOZE, SICKNESS, or FRUIT JUICE
< 50, 38 / 33, 25>[100] RESTORE ABILITY, CONFUSION, HALLUCINATION,
HEALING, EXTRA HEALING, SLEEPING, HOLY WATER, or UNHOLY WATER
< 75, 57 / 50, 38>[150] BLINDNESS, INVISIBILITY, MONSTER DETECTION,
OBJECT DETECTION, or GAIN ENERGY
<100, 75 / 66, 50>[200] SPEED, LEVITATION, ENLIGHTENMENT,
FULL HEALING, or POLYMORPH
<125, 94 / 83, 63>[250] ACID, or OIL
<150, 113 / 100, 75>[300] GAIN ABILITY, PARALYSIS, or GAIN LEVEL
The first price listed is the most likely offer. The second price,
after the comma (",") is offered 25% of the time. Prices after
slash("/") are offered to tourists below level 15, and to anyone
wearing a Hawaiian shirt or t-shirt. For ambiguous prices (75/50),
repeatedly drop the potion until you see the other price.
(sell prices for shop-owned potions are more complicated and
not described here)
* (q)uaff the potion in the following environment: (Uses up the potion)
On a level with a sink (to land on after leviation).
On a level that has both monsters and items somewhere.
Lock yourself in a safe room with your pet,
in case of paralysis or sleeping.
After #dip-ping a unicorn horn.
At full hit points.
Not hallucinating.
Non-cursed potions only.
NOT wearing sustain ability ring.
Avoid the most expensive category, to avoid wasting valuable potions.
Most potions will auto identify when (q)uaffed. Use "\"
command to see what the potion was.
Others:
<"This burns..."> ACID
<"Ooph! This tastes like liquid fire!"> BOOZE
<"This tastes like (fruit) juice."> FRUIT JUICE or SEE INVISIBLE
<"Wow! This makes you feel good/great!> RESTORE ABILITY
* If you get this far and have not identified the potion, I recommend waiting
until you get a scroll or spell of identify. Or uncurse the potion with a
scroll of remove curse. Throwing potions at monsters
for identification seems too wasteful to me.
Scrolls
* Is it "unlabelled"? (r)ead it. : BLANK
* Is it a stamped scroll? : MAIL
* Did you find the scroll in a one-space closet by a room? :
(probably) TELEPORTATION
* Did you find TWO of this scroll in the first level of Sokoban? :
(probably) EARTH
* Did the scroll turn to dust when you picked it up? :
cursed SCARE MONSTER
* (d)rop the scroll in a shop
Offer price<A,B/C,D>[base price] SCROLL TYPE(s)
-----------------------------------------------
< 10, 8 / 6, 5>[20] IDENTIFY
< 25, 19 / 16, 12>[50] LIGHT
< 30, 23 / 20, 15>[60] ENCHANT WEAPON (or BLANK)
< 40, 30 / 26, 20>[80] ENCHANT ARMOR or REMOVE CURSE
< 50, 38 / 33, 25>[100] DESTROY ARMOR, CONFUSE MONSTER,
SCARE MONSTER, TELEPORTATION, GOLD DETECTION, FOOD DETECTION,
MAGIC MAPPING, or FIRE
<100, 75 / 66, 50>[200] CREATE MONSTER, TAMING, AMNESIA,
or EARTH
<150, 113 / 100, 75>[300] GENOCIDE, PUNISHMENT, CHARGING,
or STINKING CLOUD
The first price listed is the most likely offer. The second price,
after the comma (",") is offered 25% of the time. Prices after
slash("/") are offered to tourists below level 15, and to anyone
wearing a Hawaiian shirt or t-shirt. For ambiguous prices (30/20),
repeatedly drop the scroll until you see the other price.
(sell prices for shop-owned scrolls are more complicated and
not described here)
Prepare to (r)ead the scroll:
* Have you ruled out scroll of amnesia?
N - STOP. Do not read this scroll. Use a scroll or
spell of identify to identify it.
* Is the scroll cursed?
Y - Do not read this scroll. Use a scroll or spell of
identify to identify it.
* Have you ruled out scroll of punishment?
N - Ensure the scroll is blessed before reading this
scroll. Or, ensure you have a boulder and pit nearby,
or a spell of remove curse before reading this scroll.
* Have you ruled out scroll of fire?
N - Stash all other scrolls, potions and spellbooks.
Stand well away from pets and peaceful monsters.
Prepare to take some fire damage when reading this scroll.
* Have you ruled out scroll of destroy armor?
N - remove any armor you do not want destroyed before reading it.
* Is your weapon at maximum enchantment (above +5)?
Y - wield a different weapon, in case the scroll is enchant weapon.
* Is your armor at maximum enchantment (above +3)?
Y - remove this armor, in case the scroll is enchant armor.
* Have you ruled out scrolls you consider to be extremely
valuable? (perhaps charging, genocide, taming, scare monster, enchant armor)
N - identify this scroll with a scroll or spell of identify
* (r)ead the scroll under these conditions: (uses up the scroll)
At full health
Not blind
Not confused
Not hallucinating
Not engulfed or underwater
Wearing at least one piece of armor
Wielding a weapon
Some food is on the ground
Some gold is on the ground
On a normal, mappable level
Most scroll types will autoidentify when read.
Others:
<"Your hands begin to glow red"> : CONFUSE MONSTER
<"You feel like someone is helping you."> : REMOVE CURSE
<"You hear maniacal laughter ..."> : SCARE MONSTER
<no message> - TAMING or CREATE (invisible) MONSTER
(Is there an invisible monster next to you now?)
