With reclaimed genuine parts, if they were tested adequately (might be very very difficult, though to do that) and clearly sold as reclaimed, and marked some way, I wouldn't have any problem with it.
If they made it possible for value-conscious people to use something again that otherwise would go into a landfill-good.
How to prevent them being sold as new? Only deal with manufacturers designated authorized vendors.
Like on ebay, lots of parts are sold as used. They usually work fine, and are very useful for people like me.