"I think I would worry more about toxins than taste." Dkq, considering the additives and scents in many detergents, I think I would still be worried after the thing was washed.
My niece found out the hard way, that any tiny speck of food or grease on one of those 'supposedly' safe microwave bowl caddies, can cause a fire. If I make any for gifts, I always include a note saying that it should not be considered to be microwave safe and should be used only after the food has been removed from the microwave.