Shareholders receiving such an offer should simply ignore it. There is absolutely no reason to sell your shares in such a transaction below market value. If you want to get rid of your stock, all you need to do is get online or call your broker and sell at the higher market price. Below-market tender offers are becoming increasingly common.
Hucksters usually select companies whose stock prices have fallen significantly in the market.
Shareholders accepting such an offer are making a costly mistake. I'm not sure why an investor would accept a low-ball tender. Some might tender their shares without reading what they're signing. Others could be relieved to be extricated from a poor investment. A few might not even realize that the tender price is below the market price.