Have you ever redirected a page hoping to see a boost in rankings, but nothing happened? Or worse, traffic actually went down?
When done right, 301 redirects have awesome power to
clean up messy architecture, solve outdated content problems and improve
user experience — all while preserving link equity and your ranking
power.
When done wrong, the results can be disastrous.
In the past year, because Google cracked down hard on low quality links, the potential damage from 301 mistakes increased dramatically. There’s also evidence that Google has slightly changed how they handle non-relevant redirects, which makes proper implementation more important than ever.

From Dr. Pete’s post - An SEO’s Guide to HTTP Status Codes
Semantic relevance 101: anatomy of a “perfect” redirect
A
perfect 301 redirect works as a simple “change of address” for your
content. Ideally, this means everything about the page except the URL
stays the same including content, title tag, images, and layout.
When
done properly, we know from testing and statements from Google that a
301 redirect passes somewhere around 85% of its original link equity.
The
new page doesn’t have to be a perfect match for the 301 to pass equity,
but problems arise when webmasters use the 301 to redirect visitors to
non-relevant pages. The further away you get from semantically relevant
content, the less likely your redirect will pass maximum link juice.
For
example, if you have a page about “labrador,” then redirecting to a page
about “dogs” makes sense, but redirecting to a page about
“tacos” does not.
301 redirecting everything to the home page
Savvy ---------------------------------------------------------------------------------------------
SEOs have known for a long time that redirecting a huge number of pages
to a home page isn’t the best policy, even when using a 301. Recent statements by Google
To read the full article:
Article source: http://feedproxy.google.com/~r/seomoz/~3/AQyJZWBikgg/save-your-website-with-redirects

