In Sims 3 Pets, I see ghosts at anytime of the day. And also one cat ghost, Piper Pixel. On Sims 3 I made the mistake of having my sim interact with a ghost the first time. The ghost moved in uninvited, burn her food, clogged the toilet and left a burning laptop on the table. So now on Sims 3 Pets, I have my sim stay away from them unless he has to capture them.