Often you can tell if a web store cannot be indexed by search engines by looking at the URL of an inside web page (the homepage, also called the index page or “front page,” will usually be search-engine-index-able no matter what). If the URL is a long string of characters that is slightly different from one user to the next (say, when you open the page on your computer and someone else opens the page on another machine), that likely means the site is using “session IDs” which search engines have a notoriously difficult time interpreting. If the URL is something simpler, such as “domain.com/category-5/product-6.php”, the page is much more likely to be search-engine friendly. The best way to check whether a web store or shopping cart software produces “search-engine-friendly” pages is to check the documentation; software that's search-engine-friendly will usually say so. Of course, as with any website, doing well in search engines still requires your site to have links pointing to it and some text on the pages. Just because search engines can index a page doesn't mean they'll return it for any searches.
