The issue here it's not the Shameless trait but it's the fact that your Sim or the invited Sim has the Slob trait, because the objective completes when you have the Dirty or Filthy floor buffs while in the inviting situation. Maxis forgot to add the exclusive hidden buffs that Slob Sims get when in a Dirty and Filthy floor in the objective tuning of the aspiration. There are other objectives Slob sims are unable to complete for this same reason, like cooking meals on a Dirty or Filthy floor and Maxing the fun motive on Dirty or Filthy floor. I fixed that along with other things here for anyone interested: Bust the Dust Rebuffed.😇
