I recently put my Stat-Trak Kraken Sawed Off on TF2Outpost and within seconds someone posts 'Want to trade for my knife?' linking me to a 'screenshot'. I clicked the link and chrome blocked it for malicious material (It attempted to send the file to my computer), and i realized it was most likely an attempt to hijack my account or a keylogger. ^ Just to show you what the post may look like if you recieve one. Only click links if you know they are 100% safe. Safe links on TF2Outpost are green if they are verified as safe.
There are multiple sites that put links through a number of checks as well to determine safety. The one I use is http://scanurl.net/