I actually think that people who think they have pure-o OCD might have subtle compulsions. You might do things that are considered atypical compulsions like checking or telling the truth excessively, asking for reassurance constantly, and even avoiding things that trigger you.
Yeah I used to know someone who had it. I've had it mildly too. It's OCD but in your head, you don't carry out physical behaviours like checking the doors are locked or the oven is off. You just have obsessive or intrusive thoughts - like repeating mantras in order to stave off something bad happening, or getting intrusive thoughts of violence / jumping in front of a car every time one passes, even though you would never want to.