Stop quoting, interviewing or otherwise promoting the views of any organisation that is not completely transparent about the source of it's funding or other types of support.
Why is this important?
Many so-called 'independent' organisations are funded by companies or individuals with their own specific financial, social or political agendas, and exist largely to promulgate those opinions. Giving air-time to them legitimises sometimes extreme or scientifically unsound views, and has no place in a true democracy.