We have learned to judge the quality of visitor submissions. We love visitors who give us a source. We have communicated directly with some celebrities or their representatives. We have a few people in some fields who give us inside information on a semi-regular basis. Every person on the site has a slightly different story.
Some areas are harder than others.
People who have recently come into the public eye are harder to research than persons who have been around a long time. But we cannot be error free. We post corrections and take our lumps. Posting corrections, some people might believe, calls into question everything we post. We look at it the other way we care enough about our accuracy to own up to our mistakes.