^^ This. Simple rule I apply: if you can't trust the seller, make sure you can test the parts upon receiving them. If sent fakes, make sure to get your money back as a matter of principle.

Fun thought: since eBay often rules in favor of buyers, it would be fun if someone would 'abuse' this: buy a good # of often-faked parts from all sellers that offer them, test extensively, and open disputes for any fakes received. That should (in theory) cause a good deal of $ losses for any seller that sold fakes.

Maybe repeat regularly, and it might remove some fakes from the market?