The scrappy pairing is exactly what it's called a pairing (Canon or not) that's hated by the fans. There are several reasons it's hated. Perhaps people would prefer one of the characters to not be in a relationship, maybe it gets in the way of a preferred ship, maybe it used to be liked but recent revelations in the story fill it with No Yay. This doesn't have to be Canon. Non-canon pairing imagined by fans can be made that cause instant disgust in another part of the fanbase.
Hello, Unknown Troper. You'll need to get known to lend a hand here.