How can I tell whether my Yixing teapot is authentic or not?

I read that there is a trick people can do to determine whether the teapot is authentic yixing or not. It said that you should pour hot water over the teapot. If the water would spread out over the teapot creating a water film (a skin of water) that it was likely authentic, but if the water would spread out unevenly as water drops, it was likely to be fake. BUT I also read about how many yixing teapots, especially the new ones, are glazed on the outside. So doing the water trick might mistakenly cause somebody to believe that they have a fake yixing teapot. Apparently the glaze can be scrubbed off with a toothbrush with toothpaste or baking soda. There are also burnished yixing teapots. How can somebody discern between burnished, authentic but glazed and fake yixing pots?

I recently purchased my first yixing teapots. I bought them secondhand. They are unused, but I am uncertain whether they are all authentic or not. Here are some pictures: http://imgur.com/a/dCmbM
The green one feels coarse on both the inside and outside. I am pretty sure that it’s authentic because of the texture and when pouring hot water, it creates a film over the teapot. Though I am uncertain about the red/brown and the brown teapot.
The red/brown one was smooth on the outside, but coarse on the inside. I did the hot water trick and the water streamed down as drops, not creating a water film. I assumed it was glazed, so I scrubbed it thoroughly with a toothbrush and baking soda and now it does create a water film, but the outside is still smoother than the inside.
The brown teapot feels coarse on the inside and even a bit less course on the outside. I am uncertain whether this brown teapot is burnished or glazed. The water trick failed. The water streams down as drops, but I have no idea whether or not this happens with burnished teapots as well as glazed ones.

EDIT: I was wondering; can anyone here identify the clay types that were used for my 3 teapots just from looking at the pictures? If so, please let me know what clay types they are. I’d like to do some research on them.