The 'visits' that you are see are not human beans, they are just hits from a software 'bot. This is something called referer spam which works as follows:
You see apparent visits in your logs from vampirestat.com (or similar) curious as to what the site is, the webmaster clicks on the link generating a real human visitor to the vampirestats site. All a waste of time and bandwidth but not the worst thing in the world. Problem is that these sites may carry exploitative code designed to recruit your PC into a bot network used to generate spam emails, run ddos attacks on other websites or worse.
Interesting info here