Not all traffic is created equal, especially bot traffic
Focusing on top-line metrics without considering traffic sources can destroy the integrity of your media buying budget. Bots are a serious problem. The Association of National Advertisers predicted that $7.2 billion in digital advertising will be lost on bots in 2016.
Become knowledgeable about what sites are sending traffic to you. Track bounce and new session rates. If both are excessively high, you should investigate further. If pages per session and session duration rates are low, you might also have a bot issue.
Use common sense. If you get a non-English site sending lots of traffic to your English-only site, that should raise bot traffic concerns.
Try to discern if and where bots are coming from and move quickly to blacklist those sites from your media strategy and buying. Also, consider finding solutions and resources to filter bot traffic for you. One company, Distil Networks,creates products specifically designed to filter bot traffic from your site.