I am also very skeptic ,but the prices are low enough on some of these parts to take a punt .I have had no trouble with any of the capacitors I have purchased ,and have bought quite a few exotics . I usually buy a couple to evaluate ,and if they are the real deal ,I will buy what I need ,and a few spares if hard to get . I generally only buy semiconductors from reliable sources,as this seems to be an area that duplicates are rife .