what is good urine? how can you tell? does it matter what critter it is from?

The artificial/watered down/cut stuff doesn't seem to get darker with time, it seems to go flat after a year or two. Another thing I know a guy did was freeze three different samples. One froze solid over night, one was about 2/3 frozen and one wouldn't freeze no matter how long he kept it in there. The real stuff has about a 1/3 that doesn't freeze over night in freezer is my experience. I really didn't know what the good stuff was until I started collecting my own. My personal experience is sometimes u can see the difference in how ur dog reacts to it also, but not always.