"Do the border "guys" do a walk through or fridge check?"
The answer is, . . . . . sometimes. Do you feel lucky? A lot depends on how you act, how you look, your vehicle, and the inspectors current state of mind. I know, I know, they (law enforcement) say they don't profile, but, that hasn't been my experience. Sometimes they check everyone, sometimes the computer just singles you out, and sometimes you're just unlucky and you find yourselves in secondary for the full monty.
Most food items are cheaper in the USA so unless there is something special that you can't buy here, don't take the chance. Make sure any prescription medications are current and have clear labels with your name on them. Declare cash amounts over $10,000 US. Wire transfers are safer.
Chum lee