Here are utilities I use to test whether a website or a link is safe:
http://www.google.com/safebrowsing/diagnostic?site=deputycio.com (replace deputycio.com in the address with the link of the website you want to test.)
There are no guarantees because nobody can possibly test everything all the time. Moreover, some threats are not recognized before they do a significant amount of damage somewhere in the world. Still, it’s good practice to test an unknown site before visiting it.