From Unearthed Arcana, pg. 94:
Stench of the Dead [Spelltouched]
The odor of decay hangs heavy on you, causing others to gasp and retch.
Prerequisite: Exposure to ghoul touch or vampiric touch spell.
Benefit: You exude a carion stench that causes any creature adjacent to you to make a Fortitude save (DC12 + you Cha modifier) or become sickened as long as it remains adjacent to you and for 1d4 rounds thereafter. You can't suppress the stench voluntarily.
There you go, a WotC published Feat with an inherent disadvantage built in.
As an aside, isn't it ironic that with this Feat, the more likeable you are (ie the higher your Cha. modifier), the more likely people can't stand your presence.
Conversely, the Charisma 3 character who takes this feat ends up, more often than not, smelling like roses and cookies. Intriguing.