Yup, that's one thing I learned. Pay attention to property lines. Sometimes, Sims can take irrational paths to do things, but it's often explained by property lines. A roaming Sim will not step into your property line, unless they want to visit you, or have been invited in. This means, that when your Sim leaves its property, it will find a specific path, when crossing over into the general neighborhood. Weird things sometimes happen, when you instruct your Sim to do something that has an elaborate animation. Sometimes the animation can put the Sim out of his/her own property line. This can result in the Sim being stuck, or leaving plates, drinks, and other objects in the street. If you get caught in a trafficway, it can cause a problem, for travelling Sims on the street.
