Everybody is always bitchin about repro signs.Why do they allow them to sell'em.
They have long been a part of the market (since the 80's). It use to be with foreknowledge that a sign was sold as a reproduction and not passed off as original. With the prices for originals going extremely high and yet new broad interest in signs constantly pushing the market a segment of people have chosen to pass off reproductions as real. At a sign show long time vendors should know which is which and represent them honestly. The price should be commensurate in value to authenticity.
The existence of reproductions and the pressure to have cheaper signage that new entrants or dabblers in signage can afford means that many vendors will bring such signs for the novice collector or person simply looking for a cheap sign to hang.
It is when unscrupulous vendors choose to pass off reproductions as authentic that the issue arises. The nice thing about a sign show is you can ask several vendors their opinion/experience with a particular sign. I know I have been approached about signs and asked to proffer my opinion as to authenticity. I do what I can to ensure I inform those people of what I know and don't know about such signage.
Whenever I have such signs I tell people they are reproductions/fantasy and price them accordingly. For example, I was able to buy one of the plastic Shell embossed signs and resell it for a minor profit the same day. The sign was to be hung outside and the buyer didn't want something valuable or whose destruction or loss would be heavy on the pocket, so it fit the bill even at the show.