Google recently launched a new function called "Exclude all hits from known bots and spiders". You can find, and turn it on, in your "view settings":
I turned this feature on for a lot of my clients. And for one of the biggest I did it only for a specific profile to see what the difference would be compared to the main profile. Here are some results:
- 12.657 sessions where excluded, what counted for 0.03% of all sessions.
- Most of the excluded sessions had Firefox 26.0 as browser.
Here's a list of all the 21 browsers (of a total of 1.700+) that had a different amount of sessions:
Some of them are obvious bots, like the Adsense Snapshot bot from Google.
It's safe to say the impact is almost nothing. Bounce- and conversionrates will not significantly drop/rise if you turn this new feature on. So my advice would be: turn it on, it won't harm your data. And your data is a very very little bit more reliable 😉