After the girls beat the Calloway Cadets for the first time ever, Tanis does finally get a trophy for her "mummy case". Her father wants to hug Shaggy and friends for making Tanis feel like a winner.
The Ghoul Dads in general—the full rogue's gallery of horror movie monsters in all their sinister glory, but at heart they're nice, normal dads who love their girls. They only get creepy when they switch into Papa Wolf mode.
Shaggy, Scooby, and Scrappy end up leaving after the "new students" show up, since that finally overloads Shaggy and Scooby's tolerance for monster-dom. As they're leaving, however, the main five Grimwood girls rush outside and start enthusiastically waving and shouting goodbye.
Shaggy and Scooby being able to hang out with the Grimwood Girls despite how scary they are. Lets put this into perspective: The two biggest cowards in animation hang out with five kids who happen to be the very thing they are afraid of and even bond with them. Friend to All Children at its best.
It's even better because they are genuinely frightened by the girls at first, and only stay at the castle because they can't get out of their contract. They quickly end up warming to them, and the girls love them.
The fact that the Calloway Cadets, despite cheating at volleyball, are generally nice guys who don't harbor any sincere dislike where the Grimwood Girls are concerned. They may exhibit some resentment to them as athletic rivals, but they ultimately sneak out of school and borrow one of the military helicopters to rescue them from Revolta's creepy castle. "It's the Calloway code to help ladies in distress," even if those ladies are spooks.