I'll start by saying...I love that more people are talking about mental health struggles; I love that so many more people know the name of different diagnoses, and even know some of their symptoms. Sometimes I'll hear people say "I was being SO OCD" or "I'm so depressed after reading that"; a well intentioned comment that can sting for the person with diagnosed depression or OCD. While the intention may be good, to normalize mental health struggles (as in: "aren't we all a little OCD?"), the message is flawed and in short--no, we're NOT all "a little OCD". When we reduce a mental health struggle to a single version of itself, a single symptom, or imply that a OCD is "just" something that makes you arrange your bookshelf just so, or depression is "just" a fleeting emotion you experience after reading something sad, we're taking away from the lived experiences of those who are actually struggling, in this moment, with those symptoms. IMO, what is behind comments like this is the tendency to realize that many of us (who don't have any formal diagnosis) engage in habits that resemble diagnostic criteria for other conditions, disorders, or even illnesses. Realizing that "hey, I do that--" isn't in itself bad; it's actually pretty awesome. It normalizes mental illness, it normalizes disability and it works towards destigmatizing it. But, and it's a BIG, BIG but, just because you can identify with one aspect of a person's struggle doesn't mean you are "right there with them"; having moments of distraction, which we all do, isn't the same as having persistent symptoms of ADHD. Having occasional joint pain isn't the same as having chronic pain. The reason it's easy to identify with many traits of mental illness, in particular, is because the criteria for a diagnosis is not just presentation of symptoms, it's also persistence, level of impact, and duration of those symptoms. The good news is, we can empathize with individuals who are different from us because of these shared experiences; the bad news is, we have to recognize the limitations of our shared experience. In short, many diagnoses are reached because habits or symptoms that many people have progress to a level (of intensity, duration, or persistence) that interfere with day to day living. So yes, you may also sometimes struggle to pay attention in a lecture, and no that doesn't mean you know what it's like to have ADHD. It especially doesn't mean you were "being so ADHD". And yes, you may like to colour code your closet, may be particular about how the dishwasher is loaded, or even have rigid ideas about how a fitted sheet should be folded and no that doesn't mean you know what it's like to have OCD. It especially doesn't mean you were "being so OCD."
So while I'll never judge a person who makes a comment like that, I will take the opportunity to (respectfully) explain the impact of comments like that, and offer an alternate word that better communicates the intended meaning. "Oh, you mean you were being so ...particular? So, specific? So, precise?"