Dungeon Crawl is much more balanced toward letting the player having fun without always being annoyed by stupid deaths (that are usually breaking your fun) regarding unidentified object or even cursed objects that are going to kill you 50% of the time in most rogue like, have a lot more counters and are much much less lethal as you have always ways to survive.
Nearly most of the time, you're not going to die from bad luck in regards to testing potions (unless you drink a poison potion at level 1 without any healing potion in stock, your organism will never counter the potion before your few hit points will be out).
Usually never try potions at level 1 anyways, while scrolls are much harmless.
Usually, if you have no identify scrolls and want to drink potions try to drink the ones you have in higher number first, usually in the dungeon you'll mostly find more positive potions than negative ones.
For the potion i have in small quantity and don't want to waste identify scrolls on them (better keep those for the items in my opinion) , wait until you are at high level, you should have health , and hopefully enough positive potion to counter the bad ones.
Most of the scrolls are not developers jokes made to kill the player, i met very few immolation scrolls by example and most of the time i had enough health to not die, most of the bad scrolls you'll find are more about cursing your equipment, and you hould be able to find many remove curse scroll.
That's exactly why i love it, and ceased playing nethack by example.
Though be very cautious , as rotting, badly mutating can be very annoying if you don't have any counter potions, and poisonning yourself when drinking one at low level without any health potion in the inventory