Don't you have to heat it up? Unless you get the temperature in the level, it becomes questionable. Especially since some of these testing companies make you wait a long time to prevent successful substitution. They do it on purpose to throw off the temperature of your synthetic urine.

Substitution isn't a bad concept if it's done right, but you gotta have a back-up plan if substitution fails because you got caught up. You can use your real urine that could be clean if it came down to it. Plan A, and Plan B.