Back in my early days of gaming, production quality equaled legitimacy on my eyes. Therefore, Mayfair Games "Role Aids" line was in and Judges Guild was out. Very foolish cutting out Judges Guild like that, but I was a teen with limited funds. There was no internet with a quick way to find a review on the next great gaming product - appearance was everything, at least for me.
Dark Folk isn't a bad product at all, although it is a bit inconsistent in quality if memory serves right (the Troll adventure "is designed for a party of 6 to 8 characters of 5th to 8th level of ability with at least three magic items specifically designed to neutralize Trolls - emphasis mine).
Come to think of it, I'm not sure if I used any of the included adventures, but the background fluff and sub races were pretty cool. I may just steal some of this for the current campaign.