If a test is for probation, a work injury or accident- they have cause and will watch you drain.
If it's pre-employment, they will not watch. But, often they give a physical and you need to remove all your clothes and get in a gown- that will eliminate any chance of hiding something before the test.
Peronally, I used my Urinator (look it up) at least 5-6 times and have lent it out at least 10X. Never a problem.
AND, the comment about them finding urine from a pregnant woman- is also bullshit. They don't test for that and would have no reason to. These tests add up cost wise and businesses already gripe at the expense of it all- they're not testing above what's necessary. Another words, they aren't testing for pregnancy for a guy. So, lots of false spewing on here, for sure!