Higher Quality Scores typically result in:
higher costs and lower ad positions
lower costs and better ad positions
less overall impressions
faster delivery of daily budget
- Ad auction eligibility: Having better quality components typically makes it easier and cheaper for your ads to enter an auction. Our measures of ad quality also help determine whether your ad is qualified to appear at all.
- Your actual cost-per-click (CPC): Higher quality ads can often lead to lower CPCs. That means you pay less per click when your ads are higher quality.
- Ad position: Higher quality ads lead to higher ad positions, meaning they can show up higher on the page.
Read more here: https://support.google.com/adwords/answer/2454010?hl=en