Items found in locked rooms are less likely to be cursed than items found in regular rooms.
Items found in Skeletal Remains which generate a Wraith are from the Hero's remains from another game. They are always cursed, but won't be degraded, unless it was degraded when you died with it in the previous game.
The weapons and armor generation algorithm is more likely to generate equipment with a minimum strength that matches your current maximum strength (according to the number of Potions of Strength generated). That means that if you find a high-tier weapon, or armor, in the beginning of the game, it is more likely to be upgraded than degraded, or cursed, and inversely, if you find basic equipment later in the game it is more likely to be cursed.
Here are a few strategies to assess items before the auto-identification kicks in:
If you've just started the game, the tier-5 and tier-4 weapons, and Plate Armor, will always be too heavy for you.
The slowing of the speed when you use an armor above your strength is quite easy to notice, so just equip an armor and compare your speed to the enemies. That will give you an idea of its modifier.
The same goes with weapons and the accuracy penalty. If you keep missing your enemy, then the weapon modifier is too low for your strength.
For weapons/armors that are not above your strength, with some experience, it is possible to estimate the modifier from the type of the armor/weapon and the damage prevented/dealt.
If you know a weapon/armor/ring is not cursed (or don't know but are brave) and want to know more about it, you don't have to use a Scroll of Identify - you can just equip the item and it will auto-identify: