The results are self serving nine times out of ten.
They know what result government agents and purse string holders want and that is the result they are expected to give.
Giving the right result is job security until you get caught as a liar in court.
Then everything you have ever said before a judge is called into question as potential perjury.
Government labs in Texas have been most fruitful at providing false witness and false testimony given the wholly corrupt courts there and despicable judges and attorneys who will eventually become favorite political figures of banks and corporate interests there due to the inequity that they oversee.