Repro carts are fine if its a of a game that was never released in the USA and English translated, or taken from a Prototype that was never released. I love those, I own several myself. And buying them any idiot knows it's a reproduction.
If its a repro of say NWC90 it's fine if it looking nothing like the original. Like the one that RetroZone sells. (see pic)
The ones I hate with a passion are the carts like Little Samson, Stadium Events, Flintstones etc that are people trying to make a fast buck by fooling a buyer that it's an original. It makes me second guess a game.
I remember ordering a repro of Pepsi Invaders, The guy even offered to send it with no label so it can look like the original.
I told him, NO. Its a repro, So I picked out a cool label for it.
Here's a Pic of some of my NES repro carts. Most are Prototypes or English Translations that never got released in the states.
And the few that where, (NWC90 and the 3 Adult games) look nothing like the original. In fact I'd still would buy the original If I found them at a price I could afford.