>you aren't guilty of a crime unless you know that the goods actually are stolen.
Unless you're in a jurisdiction where the knowledge element can be satisfied by whether a reasonable person would suspect that the property was stolen. In that case you could be found guilty.
Which thankfully, does not apply to criminal charges in America. Where an intent element of "knowledgeable" must be proved, it must be proved that the specific individual knew, or should have known X. "Should have known" is a catch-some for people who willfully ignore what's going on right in front of them, but it does not encompass what a reasonable person would have suspected.
You're confusing the standards applicable to tort law (another person sues you for damages) or regulatory infractions (government sues you for money) with criminal law (government tries to send you to jail/prison).
Unless you're in a jurisdiction where the knowledge element can be satisfied by whether a reasonable person would suspect that the property was stolen. In that case you could be found guilty.