One of Google's engineers, Benson Leung, has been testing out a selection of the USB Type-C cables and adapters that you can buy on Amazon (thanks Ars Technica). Worryingly, a high percentage of them aren't fulfilling the USB Type-C specification, particularly the cheaper ones. Leung has been leaving bad reviews for the offenders on the respective product pages.
So far, Leung has tested 10 of them, and only three have passed. The Belkin, the iOrange-E, and the Frieq cables are all good, but they are more expensive, up around $20. There are cheaper ones available, but of the ones tested so far, they just aren't up to snuff.
For the most part, the third party USB Type-C cables have been fine for charging smartphones, but using them on higher powered devices (Leung has been testing them on a Chromebook Pixel) probably won't be useful. In fact it might even be harmful to some of your devices if you try.
For example, Leung said that with CableCreation's micro-to-Type-C adapter, "your phone, tablet, or laptop computer may attempt to draw 3A, which may be more than the micro-b to A cable you attach to this adapter may be able to handle. This may cause damage to whatever cable, hub, pc, or charger you plug into this."
The reason behind the problem is mainly to do with how the cables handle going from a Type-A to a Type-C connector. In the example above, the cable was only using a 10kΩ resistor, when it should be using a 56kΩ.
They may be a little more expensive, but it's advisable to use official USB Type-C cables and adapters for now.