A bad doctor/other professional can taint your idea of all of them, but it doesn't always have to be like that.
I took an overdose when suffering with PND and was rushed into hospital, was sent home a day or so later, only to end up with really awful pains in my back.
Went to my doctor, told him what I'd taken etc, he told me it was constipation and I would be fine.
Two days later still in agony so I called NHS direct who said to have a urine sample sone incase of a kidney infection.
Went to my doctors, the receptionist was fine about it, was just going to send off my sample without me even seeing the doctor, but he came out and said not to bother, I was fine.
In the end a friend took me to the emergency docs who asked where my pain was and sent me straight to hospital, my kidneys had failed. I was very ill and I still think that doctor was negligent in the extreme. But I do try to meet every doctor I deal with with the mind that that doctor was just a bad doctor, and that not all ofthem are.
Thankfully I've not been proven wrong.