To add salt in my wounds, I notice different stuff in the /var/log/nginx/access.log (not error.log), such as:
192.168.1.1 - - [30/Aug/2015:05:47:29 +0800] "HEAD /App_Config/Security/GlobalRoles.config.xml HTTP/1.1" 404 0 "-" "Mozilla/5.0 (compatible; Nmap Scripting Engine; http://nmap.org/book/nse.html)"
192.168.1.1 - - [30/Aug/2015:05:47:29 +0800] "HEAD /sitecore%20modules/staging/service/api.asmx HTTP/1.1" 404 0 "-" "Mozilla/5.0 (compatible; Nmap Scripting Engine; http://nmap.org/book/nse.html)"
192.168.1.1 - - [30/Aug/2015:05:47:29 +0800] "HEAD /sitecore%20modules/staging/workdir HTTP/1.1" 404 0 "-" "Mozilla/5.0 (compatible; Nmap Scripting Engine; http://nmap.org/book/nse.html)"
192.168.1.1 - - [30/Aug/2015:05:47:29 +0800] "HEAD /sitecore/system/Settings/Security/Profiles HTTP/1.1" 404 0 "-" "Mozilla/5.0 (compatible; Nmap Scripting Engine; http://nmap.org/book/nse.html)"
192.168.1.1 - - [30/Aug/2015:06:12:51 +0800] "HEAD / HTTP/1.1" 200 0 "-" "Cloud mapping experiment. Contact [email protected]"
192.168.1.1 - - [30/Aug/2015:06:12:52 +0800] "GET /clientaccesspolicy.xml HTTP/1.1" 404 168 "-" "Cloud mapping experiment. Contact [email protected]"
Apologies for the 192.168.1.1 nark, since I am behind a NAT. :(