>>76059871. Measure how much time they spend in public. If they are in their room 24/7, there is a good chance they are a Cirno poster.
2. How many friends do they have? If they don't have very many, they could be a Cirno poster.
3. What kinds of friends do they have? Do people only hang around them because they cling, or do people voluntarily take the time to be with them? If it is the former, you could be dealing with a Cirno poster.
4. Do they have a girlfriend? If not, they might post cirnos.
5. Do they visit 4chan /bant/? if so, they could be a Cirno poster.
Tally up the criteria they follow and if its all 5, there is a good chance.