Clicking on a colour in the shop does not make your mouse wear it. It just resets the shop mouse animation thing(if you click the colour fast enough you can see that it does something to the mouse) I wanted to buy a colour but I dont know if I should now because I dont know what it looks like.
But it works if i dont wear a fur

Yes, same thing happening here.

but if you want to see an outfit before you buy it, you can use this.