It is not only for you, If you look at the analytic of Your website, Organic traffic will have less bounce rate, then comes the referral or direct traffic based on your marketing methods.
But mostly the paid traffic tend to have more bounce rate mainly due to targeting incorrect audience and certainly Adword sends more invalid traffic may not be from spammer. But for those invalid clicks, you are paying to adwords.
Some examples of invalid click for which you are paying
- Click from your competitors
- Click from your SEO people, who analyse the top ranking Ads
- Click from keyword researchers who clicks on the Ad
- Click from analyst who clicks on your Ads without having any indention of doing business with you
I am very confident that, You could be paying at least for 20% ~ 25% clicks which are not valid. (may not be from spammers)