I have a site thats getting a lot of referral spam in google analytics both for referred traffic and organic traffic (where they place the their site name in the keyword field).
Because its all bot traffic it has always has a 100% bounce rate which in turn is skewing the actual bounce rate average.
Would blocking the referral spam by using the techniques listed here : http://www.cgcolors.com/blog/block-unwanted-referral-traffic-google-analytics-report/ - reduce my over the bounce average, and thus possible have a positive effect on the sites rankings (as bounce rate is a ranking factor)