What about a dealer for example who makes a MM Re-fake - does a dealer need to tell the buyer it's not genuine?
They should, but I doubt they would. I guess like all things its a case of buyer beware, do your research before handing over your cash.
Buyer beware doesn't cut the mustard when a company or person in business is selling. The Australian Consumer Law and state Fair Trading Acts all impose obligations, such as a prohibition against misleading or deceptive conduct - and silence can be misleading or deceptive conduct in the appropriate circumstances.