I run various adwords campaigns to bring additional traffic to my websites. However recently I was listed as having low quality scores for my various campaigns. This meant that my adwords campaigns were no longer showing up.

Quality scores are affected by a number of things. This could mean that 1) you have a low quality landing page which has either viruses, with the sole purpose of collecting information, or even just websites that only show ads will be given low quality scores.

Google has a blogspot website that lists ways to improve your adwords quality score to help get your ads showing once more.