"Can't be crit" vs "critical fail"

[Centuros]

Does being immune to lucky hits also allow a monster to be immune to the penalties of being really bad at resisting an effect? For example, the Ooze cannot be crit, but would it take more damage if it failed to dodge Electric Arc by 10 or more? What about spells that only do their main selling point on a crit fail like the save-or-sucks?

[Fuzzy-Wuzzy]

It does not. Being immune to critical hits isn't a matter of being luck-resistant, it's a matter of not having vital organs to be hit (or having them in the wrong places, or whatever). They still suffer fully from critically failing a save.