Well as someone whose child has recently been diagnosed with ASD, I can categorically state that I would much have preferred to hear that the problems with his behaviour were down to bad parenting as then I wouldn't be dealing with a child with special needs, he wouldn't face a life of struggling to fit in, form relationships and manage in the everyday world and I would have been able to do something about it.
Some of his behaviour may also appear in a child who has not been properly disciplined or who is just being 'naughty' and I was certainly criticized, but now, it transpires that it is down to him not being able to process information, hyposensitivity to touch and hypersensitivity to sound that made him behave the way he was. We are now taking a different tack on how to deal with it.
However I have been in the position where I've gone "There's something not right here" but so many were quick to judge and call it poor parenting. His school, his paediatrician, SALT and the edpsych disagree.
There have been some pretty insulting things said on this thread.
I have met a lot of parents with children who have been diagnosed with a range of conditions, from AS, HFA, ADHD, ADD, OCD and ODD. Not one of them is happy with the diagnosis and all of them wish they had NT children or that it was down to them.
To get a diagnosis isn't as simple as going to the GP and saying "Ooh he never stops he must have ADHD" and the GP nodding sagely, writing a scrip for ritalin and kicking then out of the door.
Most diagnoses take months and are done by a multi-disciplinary team of specialists. You do not get a diagnosis unless your child had a condition and in my experience when you do get one you don't go "Hooray, its not my shit parenting" you are way more likely to cry. Lots.
Going to the doctors, getting a referral and going throug the hell that is diagnosing conditions on the autistic spectrum is not an easy way out, a way to relieve guilt or a way to excuse bad parenting. Its a fucking shit thing to have to do, especially when you have to deal with ignoramuses who hoik up their judgypants and come out with rubbish.