This might explain things! I found a recipe for chocolate on wikihow and here are the ingredients:-
Cocoa Bean Method (Advanced)
Cocoa beans ( 1 lb or 0.5 kg is a good amount to start with)
You can also buy cocoa nibs and skip Steps 1 and 2
Nonfat coco powder
1 vanilla pod (optional)
At no point is palm oil required in this recipe. So what is happening is that the chocolate companies have substituted the cocoa butter with palm oil and thickening ingredients so that they can sell the cocoa butter to cosmetics companies at a higher price. Hence the nasty bitter taste (the additives used to harden the chocolate) and the slimy texture (the palm oil).
This is coming at great cost to the environment, because palm oil production is endangering very sensitive habitats around the globe. Cocoa butter is produced as part of the bean which produces the cocoa powder, so the cost to the environment is much lower.
And the chocolate companies are creaming off the profits for something which is essentially not chocolate, but cocoa flavoured hardened palm oil. Yuk.