Ok, since the diagnosis I have had a few eye rolls. It's just an excuse to get away with being lazy. It's attention seeking (lol, the irony of that didn't occur to me until I wrote it). In children it is just a lack of discipline.
To be honest, had you asked me a few years ago, I would have had my doubts too.
Yes, it isn't perfect. MRI scans isn't part of the testing. People are misdiagnosed, in the same way they can be misdiagnosed with many things. But it IS a real physical condition.