A face that is ugly due (at least in part) to the use of plasic surgery. Whether in an attempt to correct flaws or just to improve a decent face, sometimes the use of surgery causes recipient to have a Margarine face.

when you've done something so cringe you can't stop replaying it in your head and it stops you from getting on with your every day life

A female with an attractive body, but a "marginally" attractive face(hence the use of the word "margarine"). A margarine face is a female whose face barely exceeds the minimum requirements for an attractive face, as not be ugly. A margarine face is slightly more attractive than a butter face, as a butter face has no facially attractive features whatsoever.

When the face of a woman is actually the most attractive part of her. This is the opposite of butter face, in which everything about her is hot but-her face.

As opposed to a butter face--a girl with a hot body but an ugly face--a margarine face is a girl with a hot body, but an average face. A margarine face is better than a butter face because margarine is not as bad for as you butter.

A female with a gorgeous body, but a face riddled with acne and oil.

A girl/woman who would normaly be considered a butter face but only has half of nice body but still has a considerably unattractive face. This could be a girl with a nice ass and small titties or vice versa.