I think the distinction should be made between a "trainer" and a "coach." A trainer is someone who is generally looking to get people back into shape or take their body to the next level of fitness. A coach is someone who is more in tune with people who have goals that are more oriented toward strength and lifting. I have a buddy who is a coach and takes BBers all the way up to competition and another buddy who is a powerlifter himself and also a coach. You will never hear stupid shit come out of their mouths because they are very specific to the outlined plan or routine.
Personally, one of my best friends who works out with me is a "trainer" who mostly works with fat ****s and housewives looking to get or stay in shape. But, when we work out together he helps me follow the routine we set out to accomplish to a T. So, some of these guys can be 2 different people depending on the situation, and the good ones know their place in those situations