As it stands, the system uses an auction system to determine which ads to place next to search results, Google rates these ads on how much they pay, the click-through rate and more recently how quickly the advertisers page loads as well as using a static measurement of value in evaluating whether to display an advertiser's ad for a specific keyword.
The new system, announced by Google this week, will involve ad quality being judged at the time a user makes a search and will be tested on a small set of users before trying it with the majority.
Google said on its AdWords blog "We are replacing our static per-keyword Quality Scores with a system that will evaluate an ad's quality each time it matches a search query. This way, AdWords will use the most accurate, specific, and up-to-date performance information when determining whether an ad should be displayed."
The search engine giant also says, "We're replacing minimum bids with a new, more meaningful metric: first page bids. First page bids are an estimate of the bid it would take for your ad to reach the first page of search results on Google Web search."