Actually you can say that - they are supposedly held to a higher standard than the rest of us, because they do that job.
I'd have to say all the social workers I've ever known were good parents, but that was in a small town setting- a different sort of people.
I do believe that it is A. a very hard job to do - and one I cannot do, because I did my internship with the abuse reporting division - lets just say I'd be in jail for what I'd do to those parents for what they did to their kids.
B. That there are a lot of unqualified, borderline incompetent people doing that job in larger cities.
C. Their own inadequacies bringing them to the job? Could be. I've met several counselors/therapists who are like that. (I'm also too normal to be one of those - I was never abused as a child or adult, no major traumas, and was taught to take personal responsibility for myself)
Personally, I'd choose to not let my kid be around them, or if it was unavoidable, talk to my kid abou their behavior - and let him do the talking as to what he thought they did wrong. Good way to teach morals to your kid as well.
BTW, social workers ARE indeed trained to be role models. Some just can't manage to hold up to that training.