dtgreene: From the few roguelikes I've played, I've decided that I really don't like having consumables not be identified.
Ryan333: Yep, I agree -- unless (1) you can save-scum (which I **REALLY, REALLY** don't like, so I actually don't consider this a viable "solution") or (2) Identify scrolls/spells/doodads are very plentiful and/or shopkeepers can identify items for you and shopkeepers are reasonably accessible (i.e. Diablo style: travel back to town, talk to the "Stay a while and listen!" dude, identify your items).
Option 2 intrigues me, in that it presents another strategic element in that you have to consider which items you will identify immediately versus which you will save to identify later. So, if you only have one "Identify Scroll" and already have a magic suit of armor but are using a mundane weapon, then you might put off identifying another suit of armor and instead identify a weapon. Again, assuming that you had a *reasonable* number of Identify opportunities through consumables or vendors... yeah, I could run with that kind of system.
The problem with consumables is that you can't identify something through experimentation and still be able to use them later.
(Gameplay spoilers for Shiren the Wanderer)
One good example of identifying items by experimentation that's done well happens with Shiren the Wanderer's pots. For those unfamiliar with the game, a pot is an item that you can put other items (but not other pots) into, and which will (presumably) store the item; to get the items out, however, you need to throw the pot at the wall, which will destroy the pot. In any case, identifying a pot by usage works something like this (put an item into the pot to start, then check the contents):
* Get the option to rub the pot rather than open it? It's a healing or monster pot. Use it when it's safe to do so to distinguish the two. Or it could be a pot that sucks in an item from a distance, which does have some uses.
* Game lets you select an item in the pot and take it out or use it? I forgot the name of this pot, but it's the one that lets you take items out of it without breaking it. (In a game with limited inventory space, it's quite useful.)
* Item disappeared? It's either a storage pot (items in it get sent to storage, where they can be later retrieved, even after a death) or a bottomless pot (item is gone forever; throwing it at a wall will create a pit, which can be useful if you're a thief).
* See a different item in the pot? It's either a Change pot (items in it are transformed) or a Liar pot (item lies about its contents, and may be different if you check the pot again). In this case, put some useless items into the pot, throw it, and see if anything interesting dropped out of it.
* See two of the item? Congratulations: You found the rare duplication pot! Yes, there's a legitimate way to duplicate items. (Unfortunately removed in the DS version.)
* Nothing happens? There are some possibilities still left. Some pots identify their contents. There are also unbreakable pots; throw one at a wall and it won't break.
Notice how these methods typically only use one charge of the item (few exceptions, like using a monster pot that you don't want to keep anyway), and you still have more charges to use? That's why the mechanic works fine here, whereas it doesn't work so well for herbs (which are identified in the game's 99 floor dungeon; said 99 floor dungeon has basically become a standard feature of Japanese roguelikes (at least the ones decended from Torneko/Shiren).)
dtgreene: I actually disagree with this. Unless the game is super short (like SaGa 1 length or shorter), I would prefer to be able to try out other character archetypes without having to start the entire game over.
StingingVelvet: Some people want to do everything in one playthrough, yeah. I just don't think that's very RPG-ish. Your character's choices and role should open some opportunities and close others, that's what makes these choices interesting. Even if you never replay games, it still tailors the game to your individual playthrough.
Having opportunities opened and closed like that is IMO good if the game is short, so one can experience a character fully in a short amount of time and then replay with a different character to see other paths. I don't think it works in 20+ hour games, however.