The1True
8, 8, I forget what is for
I actually think it's pretty easy to spot when a product is really based on early edition D&D or a retroclone.
Not always though. Bryce seems to get fooled by mislabeled products all the time. And, as I mentioned, there are a lot of homebrews (like what/why is Blueholme bro?), but there are also a fair amount of 'system neutral' products which deserve varying degrees of disgust. (Writing this as a guy who wrote a version-neutral adventure which I am now sitting on in an act of base cowardice...)