Discolored urine. If the urine passed is discolored to a considerable extent, or if it has a strange smell, these are clear indications of an infection of the bladder. The urine may be very dark, or it may look clouded. It can also have a bloody tinge to it, which can be quite disturbing to a patient. Generally speaking, this will also be accompanied by a bad smell. If one is experiencing any of the other symptoms of a bladder infection, it is good to check on the color of the urine, as this is one of the clearest indications of a bladder infection.