tl;dr: YES. Mostly. A few varieties are alright or maybe even good with boiling water. Houjicha is one that you're fairly likely to encounter (the kinda-roasty

tl;dr: YES. Mostly. A few varieties are alright or maybe even good with boiling water. Houjicha is one that you're fairly likely to encounter (the kinda-roasty / toasted tasting tea you get in many restaurants). But for the vast majority of green teas: heck no, it'll taste awful.