my friend was just scammed last night. she just clicked a link that a random user just sent him by steam chat message then later that night all the items were lost. My other friend was also scammed just like this one. My friend just told me through text that when someone sends you a link,as what i've observed:"please trade with my friend (*link)", please dont click it.
I hope valve really solve this issue. traders and users aren't safe anymore :(