Actually... Molotov doesn't know if Brock is in the room, but she figures it's worth a shot. And he's more likely to open the door for Spike than anyone else, so. But yeah, no, Molotov didn't bother inventing (?) a fairy robot or something to play a trick on Spike, that was a stupid thing to worry about.

She gestures for him to continue on when he looks at her, then crosses her arms over her chest like a proud little captain. It was a deliberate decision not to have him follow her! Because one, he'd probably sneeze himself to death, and two, he might just walk away. He couldn't do that if she was on his shoulder, ready to attack his head.