I use a wide variety of sieves, and use them every day. When i use one on food that contains fat or protein, like staining chicken broth, i wash the sieve carefully with soap and water. But if I’m just staining tea, or washing berries, or similar, i just rinse it well and leave it to dry. I don’t taste yesterday’s tea or anything. I think this is completely adequate.
On the subject of teapots, I use a Hario 450ml glass teapot. Teapot "Zen" 300/450ml – HARIO Europe
It’s one of those strainer inside a pot models, but the strainer is almost as big as the entire pot, so you still get that effect of the tea leaves being free in a large volume of water. I don’t like to use a strainer separate from the pot, because it’s normal to do 3-4 brews out of the same green tea leaves. If I were to pour the tea through a separate strainer, I’d need to somehow get all the wet leaves off the strainer and back into the tea pot for the 2nd, 3rd and possibly 4th brews.
My wife drinks a lot of hot tea, and she’s a big fan of Strand Tea.
As far as brewing devices go, we use one of these: