Can anyone give an an informed answer as to why not add some real pee into the cup when subbing with synthetic? If the fake is the same constitution as the real isn't it just diluting it? I've read some posts on other boards saying not to do it as well as this forum but no real reason why...? Just can't get past the lack of smell issue, I know at the lab it's no issue as far as protocalls but the security does the tests at my work and they DO have a motive for busting you , don't want them to dump the cup and ask for another sample I can't give if there is any suspicion.