If you know someone is a furry, then there is a problem IMAO.
You should never be able to identify a furry, a normal straight person, a homosexual, or a member of any other such group. To be able to identify an individual in any of these groups means that the person probably at some point made their private interests a point of discussion. I do not wish to know the private interests of others, especially when those interests seem distasteful to me. Thus, I am critical of anyone who shares their interests with the internet, the most public outlet imaginable for making said distasteful interests known.