D.W.
Yes, I would say it is disrespectful. I didn't have a great relationship with one of my grandmothers, and I dreaded the obligatory calls on holidays. We were required to at least say hi. Regardless of the person on the other end, as a parent you can at least instill that a grandparent deserves the respect of being acknowledged and have an exchange of general pleasantries.
Grandma's behavior, on the other hand, has no excuse. It sounds like she has clinical depression with all the sleeping and being negative. Is that something that could be a reality and explain her behavior?
Good luck.