Mario Sunshine Opening/Luigi's Mansion Ending: After Luigi has saved Mario from the ghosts, they decide to go outside. This is when Luigi, who hasn't emptied the vacuum, trips over a plant and spills all the ghost goo onto it, horribly mutating it. The evil plant monster then kidnaps Luigi and escapes into the desert. Mario straps on the only part of Luigi's machine left, the water sprayer, and goes into the desert to find his lost brother. One of the desert locals says they saw the plant heading to "Sunshine Town" and Mario goes there and has an adventure.
It's not a matter of optimism or pessimism, it's a matter of common sense! (half empty or half full?)