Open ports, eat my shorts!

Now that I have your attention...:-)

This has been happening so often lately it's driving me crazy.

Looking for websurfing proxies. Port scans show open ports 80,8080, or*080 (SOCKS) on any number of IPs.

I enter the IP/port in my browser.

BUT no matter where I try to surf I get the IP owner's website! Or 404 (page not found). Or "this site is under construction."

The websites I'm trying to go to are working, well established sites, and their URLs are even in the address window as though I've arrived there! But I'm someplace else entirely. Any ideas?