I analyze very carefully to avoid type-bias, and compare what I know about them to people that we can clearly perceive as that of possessing the cited type.
Like (Einstein for INTP, Nietzsche for INTJ, Schopenhauer for INFJ, Milton/Kierkegaard for INFP).. and so on..
With some I discuss typology, and those who were familiar with it and know their type well, confirm my assessment concernign the nature of their temperament.
Some, I've had take the test, and so far I've only made one mistake. Mistyped an INTJ for an INTP. I have not spoken with him in private, only heard him discuss ideas in public.
Type bias is less of an issue with INTPs than INTJs, as INTJs, with their Ni can be confined to their perceptions more (and we know Ni is strongly linked with the unconscious mind) and can easily make hasty decisions concerning ideas based solely on their perceptions which could be poisoned by their prejudices.
INTPs, tend to make decisions more based on conscious analysis of phenomena, and thus more likely to extricate themselves from their own tastes and prejudices.