When you're an Argonian and you sit down a throne, your tail completely disappears. What the heck! Is this a glitch or something?
I'm not sure why, except that maybe it clips through the chair. The game is good but it's not so good as to make a tail curl up out of the way. In creation kit, the Khajiit, Argonian, and sometimes Orc headgear have to be made on a separate 3d model, to allow fit without their ears/horns/whiskers sticking out through the sides.
Are you on pc by chance? If so, go into 3rd person view, sit down on the throne, and then open your console with the ~ key. Type "tfc 1" without the quotes, and then ~ to close console. It will freeze time, allow you to have a camera-eye view of the scene, and you can spin around and check out whether your tail sticks out the back of the throne. When you're done, open console and type "tfc" to return to normal.