I agree, it depends on how hot/warm you want the toy to be. I like my glass hotter than my man does, so 150 wouldn't be insane for me, because I like it when the toys leave a little bit of a red mark on my skin. We always start off with using the toys EXTERNALLY so this is okay, but for internal use, I would never put it in water that hot. I'd be sure to put it in one of the lower temperatures. Usually I just turn the water on 'hot' and put the toy in my sink and let the water run over it. I just feel it every couple of minutes until I like how hot it is.
My guy, on the other hand, likes it a lot less hot, closer to just warmed. He prefers it when we put it in a bowl of ice water lol