To me, it's purely variable.

If it's a G1-accurate Remake/KO being sold as a KO, it's okay.

If the seller attempts to pass it off as a Vintage original and sells it at a higher price, then it's a no-no.

Other than that, those streetside type of KOs are fine, since they do not actually purposely or successfully fool the experienced/seasoned collectors.

Personally, I got a KO Metroplex a week before Encore Metroplex was announced.
Sure made me very perplexed.