No/yes....like always, it depends
The undeads in FFXI can smell blood. So if you are heavy wounded they will come out of all holes and hunt you down (agro over a very long distance even if they are "not worthwhile").
Deodorize can prevent this and i cast it always when we hunt in undead areas. Like the one for Genkai 1. Maybe there are also some other beasts which agros in smell, i dunno. But when you hunt in undead regions its very very worthfull. Skip it to the day you need it.
