I was wondering if there was anything I could be doing on a website that would have a negative effect on my Adsense earnings and CPC? For example, does not including a privacy policy on your site get your CPC reduced? What other things might cause Google to be wary of a website, in terms of Adsense?
Not having a privacy policy doesn't affect what you are paid, but will get your account banned. All adsense sites must have a privacy policy. Ultimately, what you are paid is determined by the niche, what the advertiser is willing to pay, and where you traffic is from and how it performs for the advertiser once your visitor clicks an ad.
I believe if the CTR is too high, it might mean something is wrong in your ad placement for user friendlyness and your site could have its ads disabled. But high CTR doesn't necessarily mean that something is wrong in your ad placement, but in my opinion it will trigger a manual review of the site and a human will decide if the site is user friendly enough or not.