On eBay you don't report the seller, you report the item. There is a link in every listing to report it.
What sort of "scam" do you want to report? Bay's reporting system is mainly designed to report breaches of eBay's own rules and regulations. As regards allegedly inaccurate eBay makes it clear that they do not review listings or their content, which are the entire responsibility of the seller. eBay warns buyers in the user agreement that "they do not guarantee the existence, quality, safety or legality of items advertised, or the truth or accuracy of descriptions". Buying on eBay isn't like the shops. eBay is a jungle.
The protection for buyers is eBay's money back guarantee, that (for most items) if an item is not as described they can return it for a full refund, with the seller being responsible for the cost or return.
