I know that we at the Content Ping blog focus on online sales, but think with me for just a moment about brick-and-mortar stores. (Hang with me, online merchandisers. Sales is sales, and these real-world gems have a lot to teach us.) Specifically, think for a moment about physical storefronts and one of their many equivalents in the online world: your product page's meta data that is displayed on the Search Engine Results Page, or SERP.

This eye-catching storefront looks like a Fender amp, letting shoppers know exactly what this store is about and creatively urging them to enter.
Although online stores don't reside in an actual mall, SERPs give consumers a way to stroll through a virtual version of one. You perform a search for the term "baby stroller," for instance, and you're presented with a virtual "mall" of thousands of "storefronts" presumably leading to pages with content for baby strollers. So if you sell baby strollers online, it makes sense that you will want the content displayed on the SERP about baby stroller pages to be enticing to consumers.
Just as brick-and-mortar stores put a lot of effort into their storefront displays to entice shoppers, it only makes sense for you to do the same with your Internet storefront.
When potential customers search for a product, the results that appear are a reflection of your company, your website, and your product. The title and short description users see on a SERP comes from your product page's meta data, or more specifically, its meta title and meta description. You can't control the meta data of your product's retail page on external sites, but you have full control of the the meta data on your own site.
Cleaning up your meta data is not much different from sprucing up your storefront. If you let your meta data appear grungy or untrustworthy, shoppers are not likely to click. The thought of cleaning up meta data on every single page for your thousands of SKUs may look like a snarling three-headed dog named Fluffy. However, once the beast is tamed, keeping up with new product meta data will be easy.

You have only a small amount of space in the SERPS to show off your vacuum.
Back in the day, when vacuum salesmen roamed the earth and vacuumed your carpet in order to show you the true value of their machines, they had to use their potential customer's variably sized, and possibly tiny, patch of carpet to demonstrate. These days, we know we are allowed exactly 220 characters of our customer's SERP space to prove a vacuum's quality.
Just like a storefront permits a limited amount of physical space, each search engine permits a limited number of characters for each webpage. Google allows 65 characters for the title and 155 for a meta description. If you don't write these yourself, the search engines will take whatever relevant copy they can find from the page and display that as your online storefront.
To illustrate the concept of meta-data-as-storefront, I Googled "Eureka hand-held vacuum." The following four descriptions are just a few of the thousands that compete with each other for your attention. Let's start with the poster child of great hand-held vacuum meta data.

Eureka! This description is excellent. Among the multitude of other available storefronts, Eureka has made its brand and product stand out with clear product name and information. If you need a vacuum for tight corners, this is worth clicking. Simple and easy.

This is like hanging a "closed" sign in your door, covering the windows with black paper, and replacing a couple letters in your store's sign with triangles. No one has any idea what is inside, nor why they should want to enter.
Keep in mind that you can spend a great deal of resources on SEO to make sure your pages appear near the top of the SERP, but if you don't have clean meta data to entice your customers, your efforts will be for naught.

Boppy pillows? Spatulas? Aside from the obvious irrelevance, this site has all the trustworthiness of a clown trying to lure you in with opened candy.

Let's break it down to the nitty-gritty. This is a decent description, but it can be improved. I would like to know what I need to know before I make my purchase. But will I find it? The description says I will, but offers no concrete evidence that this is true. To compare it to the first one, it does not provide the direct information that tells me a bit about the vacuum before I bother clicking. If I need something that gets rid of dirt in tight spaces, I know immediately from the first link that this vacuum will fit that requirement. With this description, I do not know whether this vacuum is right until I click through and begin reading. (If this doesn't bother you, consider our culture of immediacy, where Google pre-loads the top search results in case it takes too long once you actually click.)
Because we ultimately know very little about the secret sauce of Google's algorithms, there's still minor debate about the purposes that meta data serves on the SEO front. Once upon a time, when black hatters ruled the web (or so we were told by Sandra Bullock), meta data was considered to be the Pied Piper of SEO. Throw the word "sex" in your meta data, for instance, or "Walt Disney" (but never both, lest you be associated with one of Disney's many questionable sexual references), and the masses would flock to your vacuum cleaner pages. That's all changed, and meta data no longer plays a role in search engine algorithms.
In spite of this, your meta data is crucial to your content strategy. When a user glances at the descriptions, they will determine the usefulness of your site and decide whether to click using your meta data--and everyone elses'--as their guide. They will judge it by its cover. Will they see something trustworthy and useful, or a confusing mash of words that doesn't fit what they want?
Your meta data is important. Does it look attractive and appealing, or will it turn users away when they see it in the SERP?

I suppose if I didn't REALLY need an iPad, I might be willing to look at hosiery...