Manufacturing companies should be ethically sound, meaning they shouldn't begin production, if their client hasn't signed a contract. The same goes for money; the manufacturing process shouldn't be paid for in advance or in full, until the client has seen a sample product and approved it.
One manufacturing practice that is not good is to illegally dispose of hazard waste. At one time it was ok to do this, however today, it is against the law. Also forcing employees to work off the clock is a bad practice to get into.