Yes, Google does crawl even the storefront at Zazzle. I know that Google is crawling Zazzle storefronts because I can find my storefront when I search for it on Google.
To demonstrate that Google finding storefronts doesn't really matter in the long run, I also googled "Disney Zazzle". It works out that even for a famous brand like Disney, all the options on the first page of search results at Google lead not to their Zazzle storefront, but to Zazzle's search results such as Disney T-shirts, Disney binders, and Disney gifts.
Because Disney is a trademarked brand name, all the products in the search results at Zazzle will get people to Disney's storefront if that is what they really want. But mostly I don't think even people looking for Disney products at Zazzle shop off the Disney storefront all that often.
How does this test work out with more generic search terms? I tested searching for some more general terms at Google like "pink pony poster". At the top of the list at Google, I found Zazzle's search results for gifts and posters. If most potential customers are going to give Zazzle a shot, it will be a poster on one of those two pages that catch their eye.
Does Google index specific products? Yes. From the search results for pink ponies at Zazzle, I picked out a poster that looked like it had fairly unique product name: "Little pink pony nursery children art poster". When I search those terms at Google, the actual specific poster was at the top of the list in the Google search results. But this also doesn't really matter because customers want options. This is a cute poster, but chances are far greater that a customer looking at a list of 60 posters will find 1 they like and buy it than a customer looking at 1 poster and deciding that's the one they want. Even at WalMart there are lots of options on the shelves because people like to browse.
Little pink pony nursery children art poster by Kiddosz
Shop for a Poster template or design online at Zazzle.com
So, basically shopkeepers at Zazzle should realize that SEO is important. I read some articles on the subject every now and again too because I have blog. But when it comes to my stores at Zazzle, I spend more time thinking about Zazzle's guidelines regarding things like descriptions, tags, promoting products, and other zRank tips. Over the years, I've come to realize that if I do what Zazzle suggests, then my products perform better in their marketplace and the SEO takes care of itself. Since those guidelines change over time, it's kind of an unending process. I've always got a lot of work to do. While I was typing up this blog post, I took a few seconds to change the description of this poster. It really is a lot of work to keep up a Zazzle store. If we want to have an online store in a highly competitive market like custom gifts ... we can't be passive.