Generally used to discribe a female. A swamp face is someone that has a face not even a mother could love. this cannot describe someone with just acne or a unibrow it has to refer to many problems and/or blemishes. if you can't look at this person's face without laughing or vomiting you've met a Swamp Face.
Wow that bitch is a swamp face. Look, every one in the room is puking.