Basically, the spray pattern should be conical and even, without streaming, dripping, or uneven spray occurring. This ensures the fuel is atomizing as much as possible. Here is a granular image which shows what a multi-port injector (like yours) should look like:
You should be looking at 3rd from the left.
From your image on the other question, I'm not necessarily seeing any suspect spray patterns. After you clean the injectors, any deviance in the spray patterns should be cleaned up.