Normal urine is clear and has a straw-yellow color. While the odor of urine can vary somewhat, in most cases, it does not have a strong smell. With dehydration, the urine is more concentrated and may have a stronger ammonia scent than normal. Consumption of certain foods, such as asparagus (which can impart a characteristic odor to urine), and taking some medications may be causes for changes in the odor of urine. The presence of bacteria in the urine, such as with a urinary tract infection (UTI), can affect the appearance and smell of urine. When there is an infection in the urinary tract, the urine may take on a foul-smelling odor as well as appear cloudy or bloody. A burning sensation during urination may be a symptom of a UTI. The urine may also have an abnormally sweet odor in uncontrolled diabetes, and some rare genetic conditions can also cause the urine to have an abnormal or strange odor.

Source: http://www.medicinenet.com