There are very few fake certs floating around out there. The Watson guy Art refers to seems to have made a speciality of "hijacking" dormant companies, taking them over by reactivating their incorporation in Nevada or wherever the company was initially incorporated, then issuing new certs and selling stock.
The kind of damage that can be done by this technique is fairly limited. Most CEOs pay attention to what's going on with their companies. Others, like Megas, don't.