I'm somewhat a miss over what the confusion is?  When you're browsing through the free stuff, and see something you like, click on the Details button.  The bottom line of the Details page lists the "License" for that Freebie; be it Commercial, or Non-Commercial.  If it's Commercial, then go ahead, Render and Sell!  If it is Non-Commercial; then forget about e-mailing the creator, or looking through the ReadMe.