The GM has several options when this defect is generated:-
The mutant's body secretes a substance which will attract carnivores. It might be a noticeable smell (sweet or pungent), or under the range of human senses. The character will always be the target of choice for carnivores.
The mutants aroma is exceptionally attractive to any other sentient that could be attracted to the character. This can lead to all kinds of complications. It is suggested that Hostility Field be used as a template for the effects.
The mutant gives off the aroma of fresh dung, and will always be surrounded by a cloud of flies. Suggest GM's give a -5 to -10 penalty on interaction checks where smell may be detected.
The mutant is attracted to a foul odor of the GM's choice, if a PC has this they should get a +10% XP bonus if the roleplay the defect.