If your estimated 1st page bid on the keywords you are choosing is increasing even after you adjust the bid from say .60 to 1.00 and your quality score seems to be decreasing while your bid amounts are still increasing it can affect your display rate and drive your CPC up. Check your LP's and make sure your keywords are relevant to your offer and try to use some of your main keywords in your Ad title or in the copy. If your ad comes up in a search and one of your keywords is bold and highlighted in the ad then I read somewhere that your keyword is considered "relevant" and supposedly your CPC will be lower and it helps your quality score go up.