My maternal grandmother doesn't criticize so much as she compares. My mother has just stopped making stuff for her, and we've all but cut her off at this point. Every time you show her something you've made, be it art or food or whatever, you get the same response.
"You know so-and-so makes really good X."
Every. Single. Time. Mom makes her a quilt, "You know our neighbor's daughter makes really good quilts?". I bake cookies, "You know your cousin L makes the best cookies*."
Not even bothering anymore. This is the same woman who, when I was a 18 months old, told off my mother because I kept dropping the candies my grandfather was giving me onto the floor.
Her old-as-hedge dog had a seizure a few weeks after we left, she still blames us for it. Swears he ate those little candies and that's what killed him and it's our fault cause I dropped them and my mom didn't clean them up fast enough.
That same visit was the only time my eldest aunt had visited, ever, and she brought her kids. Since they were there, my younger aunts bought their kids. So, it's me (18 months), my cousin M (16 months or so), eldest aunt's two (15 months or so and 3-4 years), and my cousin J (about 10). At one point we all started jumping on the bed.
Guess who got in trouble.
Guess who was accused of having talked the others into it.
Honestly, we have no reason to believe she likes me, my mother, or my sister. Hedge, we don't have reason to believe she likes Grandpa. She's worse to him than she is to us.
She'll sit there and nag and criticize him until he makes a smart remark back, then she'll call up my aunts and cry about how he's upset her and they have to call my mother to tell her to call my Grandpa and tell him to apologize.
For those who couldn't follow that:
Grandma to Aunt- "Call your sister and tell her to talk to your father."
Aunt to Mom- "Call dad and tell him to apologize for hurting mom's feelings"
Mom to aunt- "She lives with him, if she's upset she needs to tell him herself!"
Once again, Grandma don't' like us.
Grandpa does like us though. He'll compliment you on a job well done, he'll teach you, he'll be patient with you. He loves his kids, loves his grandkids, loves being a grandpa.
Him we'll keep.
*That's a lie. I make the best cookies. Ever. And she's never gonna get them again 'cause I don't like her.