I'm working with a global ecommerce website that allows users to filter results by brand and location. Google seems to have indexed a page that was filtered for a specific brand. How would that happen? Is it problematic from an SEO standpoint?
This could easily happen if you are using get parameters to generate the page with the filters applied.
If you already have a dedicated brand page, this could create duplicate content issues (not good). If this is the case, then you should consider no-indexing the brand filter page, adding a canonical to the brand pages if brand filter is applied, or using the options available in Google Webmaster Tools. (http://support.google.com/webmasters/bin/answer.py?hl=en&answer=1235687)