Possibly the vagueness of the instructions is part of the point. No matter how much Lottie abases herself to appease her nemesis, Skelottie can just say “Not good enough!” and throw her friends (and Dean) into the reservoir anyway.

This accomplishes the goal of revenge in three ways:
1. Lottie reputation is ruined
2. Lotte’s friends are dead
3. Lottie blames herself for point 2, because she’s a melodramatic doof like that sometimes

Come to think of it, all three points get accomplished regardless of whether Lottie does anything or not! It’s fiendish in its genius.