A great thing about wikis is that they have reminded people that information on websites as well as books are provided by real people who make mistakes. Sometimes this is seen as a failing of wikis - but this is not the case, as a properly curated wiki is often as reliable or even more reliable than other sources of information.
The lesson is this: read critically, whether the author is an expert or a collection of unknown people. Make an assessment of whether this book or website is a useful source, but remember that even the best sources make mistakes. And take responsibility for your own actions, and your own safety, as well as the safety of those you are responsible for.
The Appropedia community (those that edit and those that support in other ways) are working to build a comprehensive resource on the important questions that face humanity. We are working hard to make it a reliable and useful resource, using various tools to make this process more effective.
When we reach this goal, and have the most complete and reliable guide to human development and sustainable technologies and practices in existence... you will still need to read critically.
- Not to mention the potential advantages of timeliness, completeness, and the ability to be corrected.