Is Producttags benefited to SEO?

[Lavender]

I saw there are lots of Ecommerce websites are taking with Producttags, such as lightinthebox.com, milanoo.com and tidebuy.com.

But i am not sure whether this is really a good idea for search engine? In my opinion, too many tags (which could point to many pages) will output duplicate contents and this will do harms to your site.

However, it is also true that product tags is another way of pages index and let Search Engine crawl more of your pages. The question is how to arrange Product Tags.

Any ideas?

Thanks!