Another thing to look for is an HTTPS connection anytime personal information is requested (meaning your browser might display
https://whatever.com instead of
http://whatever.com). I haven't heard of fake sites with HTTPS protocol. Yet. Of course, if it's a free wifi hotspot, with nothing financial going on (no credit card info), there may not be a need for HTTPS, so the lack of HTTPS wherever you log in doesn't imply it's fake (unless financial info is being requested), but the presence of HTTPS is a pretty good indicator it's real.