Are old bloodworms still good to feed?

I usually feed my betta fish bloodworms but after a feeding, I am still left with some. I thaw the cube of bloodworms first in a container with water and use some of the bloodworms. After a while they lose their reddish colour and look sorta clear. The container also smells really bad. Are those worms still a good feed for my fish after its been out for a while? They havent been refrozen.