Is the ReactOS kernel clean?
In 2006, an overenthusiastic contributor caused troubles. The aftermath slash back the project for several months and stressed the relationship with Wine for some time. Since then, every possible effort is made to keep the code clean and disallow tainted developers. (that's why I wrote the comment above, to warn others) You can read a short summary on Wikipedia: http://en.wikipedia.org/wiki/ReactOS#Internal_audit