Here is a interesting article on the 1943 steel cent strip, written by David Lange of NGC. The article gives some of the background of the 1943 steel cents, and then talks about how the pieces of steel cent strip came onto the coin market. We have handled many pieces over time, and all of it was rusty to some extent--this article will explain to you why that is. http://www.coinweek.com/dealers-companies/ngc-dealers-companies/usa-coin-album-steel-cent/
There have been a lot of Chinese counterfeits coming into the coin market over the last 5-10 years, and occasionally error coins have been the target. Recently, we came across this lot of double-struck Morgan dollars on eBay, with a "Buy It Now" price of $135. They were being sold as "copies" and not as genuine, but the problem comes from them not being marked in a permanent way as being copies. If someone dishonest buys these, or if someone buys them, passes away, and their children sell them onto the market, you now have a bunch of coins out there that will doubtless fool collectors. These aren't very high quality counterfeits, and any expert would be able to tell immediately that they're fake, but to a novice or perhaps an intermediate collector, they will likely not be able to tell.
So be careful what you buy, and if it looks to good to be true, it likely is, and if you aren't sure, ask us or some other expert in mint errors/counterfeits.
As a separate but related item we'd encourage anyone with counterfeits/copies to mark there coin in a permanent way so that they will never be confused with genuine coins (obviously be 100% sure it's fake before doing so!) In this way the educational aspects of the coin can be maintained, but collectors down the road wond be duped by your coins.