Proxies are detected no matter how smart the user is. Socks are undetectable but it is advised not to cheat as there may be chances of IP getting blocked.
I agree proxies are detected no matter what along with other information however the user can spoof information to make them undetectable.
detectable:
-port of ip address : dead giveaway if you are using know ports like 8080..
-time zones of proxy ip does not match actual zone of geolocation: for example ip says you are in new york but your browser is giving geolocation of california (dead giveaway). To detect this go to google and see what time zone it renders for your searches or go to whoer/extended
-Operating system: even a proxy will not spoof your os information even if you use a proxy. if you use a proxy without spoofing os information your user agent will render one operating system and your browser will render a different os information: (dead giveaway) change your os information is browser config.
-plugins: if you use a addon or plugins can be detected for example if you use a plugin to change your user agent and advanced detection system can detect the user agent switcher plugin which is a red flag. Normally users do not use user agent switchers. change your user agent manually in browser config.
-screen resolution: if you try to sign up with the same screen resolution for every signup NOT GOOD. This is another red flag.
-dns server: most proxies do not change your dns server ip address. if you try to generate fake signups and all of your signups have different external ip address but their internal ip address or the dns ip address is the same. This is a major red flag. How can you determine? get a google analytics account and place the code snipet on your website then change your ip address with proxy but do not change your dns ip address and you will notice google analytics will only give you one unique visit even though you changed your external ip address with a proxy. both the external ip address and the internal ip address have to be changed or your out of luck. how to determine internal ip address: DNSLEAKTEST RESEARCH TO CHANGE DNS SERVER IP!!!
-flash cookies: even though you think you might of cleaned flash cookies they can be re-spawned so make sure you clear cookies with programs like adwcleaner, ccleaner, and hitman pro. or manually delete them in this folder: AppData\Roaming\Macromedia\Flash Player .... then restart your computer or use virtual os like vmware then after you clean with all three programs close vmware then restart vmware. YOU HAVE TO RESTART YOUR SYSTEM!!!DONT BE LAZY!!!
disable flash: DO NOT DISABLE JAVA OR FLASH..DEAD GIVEAWAY!
ip address/spam: if you ip address has already been flagged as spam or blacklisted do not use them...check ip address with IP-SCORE or whatismyipaddress.
FOR GOOD MEASURES CHAIN YOUR PROXIES!!!!
HOPE THIS HELPS!