I'm trying to make a cloth fall on an object (imagine a hook but on its side), and whenever the cloth tries to bend around it there are weird blocks that come up. The object has a decimate modifier (collapse) on it and the cloth has been subdivided multiple times and has smooth shading and has a subsurf mod on it. This weird blockyness of the cloth is causing it to tear as well so idk what to do. 
How to prevent this??
First: I would apply modifiers before you run simulations, so you could try applying the decimate modifier and re-running the simulation.
Second: You could subdivide the cloth some more, in edit mode. I'm not sure if you did this, but subdividing the cloth using the SubSurf modifier doesn't increase the resolution of the cloth in the calculations of the simulation.
Third: Increase the "padding" of the object. By "padding", I mean the distance from the object that the cloth will colide with. I don't know what yours currently are, but hopefully tweaking this will help. The values 'Inner' and 'Outer' are what controlls this.
