The Nikto Guard I own and I can tell you for a fact he has back printing. Pretty basic printing, but still present.
Can I ask why you are asking?
Volcano scientist does NOT have a plain back973pb2504c01
plain lavender torso973c65
plain backsand green torso973pb1063c01
plain backbright light orange torso973pb0841c01
plain backbright pink torso973pb1676c01
plaindark brown headhttp://www.bricklink.com/v2/catalog/catalogitem.page?P=3626b&C=120#T=S&C=120&O=andhttp://www.bricklink.com/v2/catalog/catalogitem.page?P=3626c&C=120#T=S&C=120&O=
plaindark orange headhttp://www.bricklink.com/v2/catalog/catalogitem.page?P=3626b&C=68#T=S&C=68&O=andhttp://www.bricklink.com/v2/catalog/catalogitem.page?P=3626c&C=68#T=S&C=68&O=
And you'll find the eBook in this article really helpful, if you haven't already seen it:
^ what @CCC said.
And to specifically answer your question - no, they are definitely not wiped or knock offs. I have purchased these and other body parts that were never in sets. Just make sure the item isn't in the Custom category and that the seller(s) have extensive positive feedback. That's all I do any more.
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