deadsea - 12:43 pm on Apr 27, 2011 (gmt 0)
I 301 redirect to remove *every* unknown or un-needed parameter. Each page template has a list of parameters they accept. Each parameter is either required to display the page correctly, optional to display a section of the page (product color), known but only for tracking, or unknown. We generally allow only the required parameters to remain on the url. Others we stash into cookies (if needed) and redirect to remove.
It shouldn't be possible to link into our site with non-canonical urls that don't 404 or redirect appropriately.