How can some deathclaws find you when you're in stealth boy?

Answer from: klr
I feel your pain. i used the stealthboy just before the billboard on the left. i then stayed up high on the rocks. when i did that i was able to sneak by them.

Answer from: Scar626
Its because they have a very high perception (or somthing like that) so high infact that they can detect players even if they're using a stealth boy

Answer from: Dalton
The Deathclaws have a high perception of 12 *this is indeed above what the player or any npc can have* and rightly, it is very hard to sneak by them. All Deathclaws are unique, but all of them have a perception ranging from 10 up to 12. Try having high sneak skill, more than 1 sneak perk, and a Stealth boy if you cant just kill them in 1 hit, like myself :P