I block all cookies by default.
This now causes a problem with Google. Some links in the SERPS are redirected. With cookies off, the redirects fail: the redirect is actually an blank HTMl page containing a redirect Javascript.
However, turning OFF Javascript makes it work again: there is a meta http-equiv refresh inside a no-script tag.
The end result is that a small number of users will have links in the SERPS that do not work. It may matter for sites with lots of privacy conscious users who block cookies.