Don't get too excited about Google +1. You need to be logged into a Google account to +1 a link you like. If you create a new account (with proxy or however) and the account wasn't used for anything else then Google will not assign any value to your +1 clicks. However, if you have been using Google services for a wide variety of normal-use activities and have a tendency to be proactive in a particular niche (e.g. cars) and then you Google +1 a car related website, that would be considered a useful indication for Google to consider your +1.
So in short: you can hire Fiverr services, create a zillion Google accounts, etc. and then +1 all your websites, but it won't impact SEO unless the Google account holder has a history that Google can analyze before determining whether the +1 selections should carry any weight.
If anyone can prove this wrong, I'm all ears!