I feel like I would have been diagnosed with OCD a lot earlier if the vast majority of screening questions (for mental illnesses in general) weren't based on the person's perception of their own behavior, in isolation. and what i mean by that is asking someone with OCD "do you wash your hands excessively?" is not a good question.
a person with OCD believes they are washing their hands the correct number of times. it's not excessive. we believe we're exhibiting best practices and helping to keep everything clean.
better questions might be, "does it seem like you wash your hands a lot more than your friends or family?" "do you get dry patches or cuts on your hands from washing your hands?" "do you find it deeply distressing, more so than how you've seen other people react, when you get something on your hands that you can't clean off right away?"
being asked "are you overly preoccupied with bugs, symmetry, and contamination?" also got "no" responses from me years ago in my life. what they didn't ask for, and didn't know, was what *exactly* I was doing in my day to day life that genuinely ate up my time and mental space to a concerning degree, but I *didn't know* that other people don't do this.
"do you spend a lot of time cleaning?" -> no, it's not a lot. it's a good amount. why?
"do you become frustrated because it seems like no one else meets your organizational and cleanliness standards - do you often 'take over' for other people because they can't do it right - do new friends seem surprised by how strict you can be about your living space?" -> oh. yeah. yeah I get it now.
if the screening questions on the mental illness test sound at all like "are you already aware you're mentally ill?" then, shocker, it's not going to work all that well!