As a conservative dad, I believe very strongly in self-reliance. I demand it. I believe that the world is a cruel place and that you need to be prepared for it.
As a result, I wrongly diagnosed my son as a lazy liberal even after a pediatrician concluded that my son at a young age had ADD (without testing). I always thought that ADD was over diagnosed - still do. We resisted medicating our son and went with teaching and consequences.
Despite our best efforts, my son continued to struggle. Another expert thought ear infections, which led to speech delay, was the main problem. Tubes fixed the problem. Educational experts concluded after IQ type testing that my son would catch up and it should not be concerning.
Third grade discipline problems surfaced again. The experts said, "Oh that's just the boy in him no worries".
My son stumbled through school, but was moving ahead until he hit a wall in 7th grade. The educational experts said, "Oh he is just a teen he will be fine". I was not convinced, so I finally pushed for tests.
He was diagnosed with ADD at the end of the school year and was taking some strong medication. (He had been on and off of meds for 2 years) In eighth grade, we were on his teachers like white on rice to adhere to our son’s special needs. All of the sudden, mid year his grades were great. But I had my suspicions that something was not quite right because he was still not applying himself. He graduated middle school. We were hopeful even though we remained skeptical. In HS (9th), my son failed 4 of 7 classes the first semester and 5 of 7 with 2 D(s) the next semester. What I realized too late was his teachers in middle school gave him a free pass. These teachers did not want to be bothered by a kid with special needs and two persistent parents. . He was not prepared for the rigors of HS.
So my advice to all who will listen, if your kid is misbehaving and underperforming and basic parenting discipline and teaching are not working - make sure you get the right diagnosis as quickly as possible. And know the laws so you can get the maximum support available to help you help your kid.
Musings of a Distractible Mind has some good thoughts on this.