There is definitely truth to these pots being excellent for tea. I
used to use glazed pots for everything until I finally found an
inexpensive Yixing (purple clay) pot. After an initial seasoning, each
pot of tea gets better and better. The only example I can think of is
a meerschaum tobacco pipe. Like a yixing pot, they are relatively
porous. After being used, the pores are filled with good essences of
whatever has been put in it, enhancing the item for the next use.

Now that being said I have two pots, one for lightly oxidized green
oolongs, and one for darker oolongs like Bai Hao. I still use glazed
ware for pu-erh, greens, whites and blacks.

-ben