Velma from "Velma" is a bigger scrappy because of bad writing:
*Scrappy was meant to be a funny sidekick that evolved into an overused joke, while the evil version of Velma was meant to be a sympathetic and complex main character. Lousy characters are easier to swallow when they are ridiculous/lame on purpose than when they were meant to be major.
*Scrappy was hated by many people, and the good people solved it by turning him into a villain. Velma was, like, the opposite of what they should've done. They took a villain and expected us to treat her as a hero, and then acted all surprised when we didn't relate to her.
*Scrappy was hated more because of what he symbolized rather than what he was. Velma deserved every bit of hatred she got.
*Scrappy was a new character at the time and failed on his own. Velma is an adaptational villainy version of a beloved character, and she failed both the audience and the legacy of the original heroic character.