There are plenty of explanations as to how to identify a fake in these threads, and yes there are "good" fakes - which are not easily spotted in the first instance, and "bad" fakes which are easily spotted even to people with little experience in MAC pigments.
As for the above comment, most people who get stung with counterfeits are people who havent actually joined the specktra community and are otherwise unaware that these threads exist... unfortunately most people are first time users/buyers and usually have no idea counterfeits exist until they come here
As for TheCollector, as I mentioned previously, she isnt the first person to discuss those sellers in particular, if you did a search you would have seen many, many posts regarding them - there isnt any benefit that I can see to one seller posting about another seller when the seller in question already has loads of pre-exisiting posts of the same nature.