Collateral or contingency dead loads should probably be ignored or neglected, but there is a 0.6 on the dead load in ASD, practice probably varies.
Some collateral dead loads will quite likely be there (i.e topping slab on precast, poured gypsum floor topping, and so on) other items are less likely to actually be installed (say, shingled roof at 3 psf versus maybe 10 psf for concrete tile), and then "hung loads" that are generally viewed as live loads as they are sporadic.