When you are asked to enter your personal or login information online and you are not sure whether this site can be trusted, you may use one of the following online security advisor services:
Sucuri Website Scanner
This is a free malware and security scanner one can use to assess security level of a given web page. Just enter the address of the site you want to check for security and get a quick result provided by Sucury. This service runs a real-time scan, as well as checks the address against multiple blacklists. In most cases you can be assured that SPAM and Malware attacks will be detected.
Norton™ Safe Web
Comprehensive website rating and reviews. When you provide a web address of the page you are having doubts about, Norton analyzes the site for safety and security. If this page hosts computer or identity threats, Safe Web will let you know. It will even give display user rating and reviews. It may even try to calculate the annoyance factor, if the site is not very user-friendly.