Come settle a sisterly argument. AIBU to wash my teapot after every pot of tea made or does it ruin the flavour?

[Nevergoogle]

Ok, so my sister thinks her teapot is seasoned by not washing her teapot in between pots of tea.

I don't drink tea, so have no idea whether the flavour is better or not, I just don't like a stained teapot and think it's a bit minging to leave old tea in the pot.

She'll be along in a minute.

come and live here then! We dont usually have chlorine in our water, I have been told, as it doesnt stand around.
It tastes very nice, but you can feel the difference on your skin when you first arrive.

Dont know why there is no scum, then - it was revolting, I remember.