Mrs. Gleeful doesn't appear in Gravity Falls to often but when she does she seems traumatized. A Redditor suggests that this could be a result of Gideon's power. The Redditor says. "After Gideon found Journal 2 and found The Magical Amulet, Gideon's mother found out about it and Gideon used the Amulet to mess with her mind." This would explain why she always has such a terrified face. In one episode she says "Just keep vacuuming." if she was scarred by something that happened between her and her son, and is conditioned to obey him.