There are some childminders who are, and let's be honest here because we all know some in RL, the "glorified babysitters". They may or may not be good childcarers.
There are other childminders, and I would like to count myself as one of them, who do regard this as a "professional" job. I am not a qualified dietitian, doctor, lawyer or whatever, but I have successfully completed many courses which have certainly given me more knowledge than what I had as a parent to my own children (who are now grown-up). I also have access to "real professionals" for any information I may need on all sorts of subjects.
I wouldn't dream of telling any parent how to care for their child, but will give advice if asked (as a childminder, as a mum myself, or as friend). However, if I was unsure or advice was needed on something serious, I would ask for professional advice elsewhere - even Mumsnet issues warnings about taking advice from each other!!
I also agree that this is a forum where, as smeeinit says, we should be able to let off a bit of steam confidentially. However, I am also acutely aware that as a worldwide parenting forum, parents will also read posts made by childminders, and I would therefore not ever make comments likely to upset any potential customers!!
And I don't want to cause a ruck!!