Having a label helped me a lot for similar reasons to FG - I could capture my demon. Looking back at my life and the way that things have gone, I can also recognise ADD behaviours there (indeed, recognising ADD behaviours in my school reports was a key element of the diagnosis). This gives me power to forgive myself: ADD is not an excuse for my poor performances in the past, but I've spent too much of my life thinking of myself as lazy and weak. I feel that I understand better why my education was so skewed towards things I liked, or why I flit from subject to subject, or why I will focus on interesting things to the exclusion of all else, or why I have such an appalling sense of the passage of time. Recognising these things (rather than blaming myself for them) has helped a lot.
I'm normal on the surface. Whatever demons I carry with me are my business, but I'm approaching 40, single, childless and seem to be attracted by, and attractive to, men 15 years my junior. Make your own conclusions, then keep them to yourself! ;o)
[Lib] Ah, but they're not just labels. They're objective realities. Saying that someone has ADD, for example, isn't just saying that they have a bunch of particular personality traits - it means that they have a particular genetically transmitted condition which causes those traits. As Fat German says, if you don't have the traits very badly, you probably don't have the condition with which those traits are sometimes associated. But if you know that someone does have that condition then you can treat it, if treatment is appropriate. Describing this kind of diagnosis as "applying labels" is as silly as talking of disgnosing a broken leg or lung cancer or any other illness or condition as "applying labels". Certainly I have found it enormously helpful to be properly diagnosed because it means I can recognise OCD things for what they are and deal with them accordingly. And this is true of many other people I have spoken to, with OCD and with ADD as well.
[BM] There is a crucial difference, though, between a broken leg and these mental conditions or constitutions. In the case of a broken leg, you can demonstrate the objective existence of a physical pathology, and there are treatments known to be effective in pretty much every individual case. For ADD and the like, no-one has demonstrated either an objective pathology, or an objectively effective treatment based on an understanding of the pathology. All we have is descriptions of symptoms that cluster together (although no individual need show all of them), vague genetic correlations, and supposed treatments of very variable effect. There may indeed be a definite thing wrong with the brains of OCD sufferers, and there may be possible treatments as effective as setting a broken bone and applying a cast, but currently, very little is actually known.