Scrolls are represented by ? and have a weight of 5. Each one has a different effect when you read it, some effects desirable, some highly not.
You may want to read about scrolls first.
Always useful scrolls
Scrolls of enchant weapon are definitely keeper, you can never go wrong with those (unless it is cursed). Keep in mind, though, that it is unsafe to enchant any weapons to anything over +5 (unless you use a blessed scroll. then you could enchant it to +7).
Similarly, the scroll of enchant armor will be highly coveted and almost necessary to get your AC to a good point. The same caveats about enchantment apply.
The scroll of remove curse is never useless, especially when blessed, but comes into its own during the endgame, as high-level spellcasters including the Wizard of Yendor can randomly curse items in your main inventory.
A Scroll of charging is especially handy to have around. Maybe you want to recharge your depleted tool or wand, unless the scroll is cursed, you can recharge it. Some objects explode after experiencing the charging process too many times, so be careful.
Useful early- and mid-game scrolls
Scrolls of identify should be kept also. Even if they are cursed, they still allow you to identify one item, and identifying items can show you the +, true name, and BUC status of the item. However, these are largely obsolete if/when you find a spellbook of identify.
The Scroll of light can be kept or blanked, but they can be handy in dungeons that are not lit. Reading it will illuminate the area you are on, this can be used to mark important stashes, or just to find specific dungeon features you might want to use later in the game. Its utility rapidly deteriorates as you progress through the game.
Scrolls with specialized uses
The scroll of genocide is a common wish with many possible uses.
While near useless in early game, the scroll of gold detection is valuable on the Elemental Planes to locate portals.
Scrolls to blank
Right off the bat, Scroll of amnesia should be blanked. It is probably the worst scroll (see its effect) and will not be very productive (unless you really want a lower wisdom and to forget some of the levels you've explored and the identities of some of your items).
Unless you are pursuing some esoteric stupid ascension trick, the scroll of punishment is also a prime candidate for blanking.
Scroll of destroy armor should be blanked if you already have a scroll of remove curse. If you are wearing cursed armor without a scroll of remove curse, you could drop all your other armor and read the scroll (this will not work if the scroll is cursed, it will lower the enchantment of the armor instead), destroying the armor. Of course, scrolls of remove curse will uncurse all cursed items that you are wielding or wearing (or everything in your main inventory if it is blessed).
Scroll of fire can be kept, but should be blacked if you have no means of getting fire resistance.