Granted there have been a few, but percentage wise it barely registers a tick on the scale.
Don't get me wrong, there are lots of excellent instructors out there, and I am sure a majority of the students are getting the training that they need. I just had the unfortunate luck to select an instructor that barely covered the minimum, and spent a great deal of the class time pushing his personal political agenda and bragging.
I knew how to handle a firearm (grew up with them) when I took the class, and still sought out venues where I could get some training and work on the required skills. I took it upon myself to do additional research on the laws and the responsibilities of CC.
In the 1770's there was a gun in every house and every person in that house knew how to use it. When the RKBA was drafted, the aspect of gun safety, liability, ect... was a non issue. 230 odd years later, it (gun safety, responsibility, training, liability) is an issue because a majority of the citizens did not grow up with a firearm.
Absolutely, keep the feds out of the game. Educate the public, and maybe tightening up the requirements a bit to include range time among other items may not be such a bad idea.