My sister (with whom our mom lives) called me while Mom was with me this weekend and asked if I could keep her an extra day. Mom was sitting nearby and I said, jokingly, "Sure, unless she gets crabby." My sister laughed. She pointed out, correctly, "She would have to take lessons to learn how to be crabby!"
Mom is 93 and has moderate dementia and severe arthritis pain. I'm not saying that none of her behaviors are aggravating or that it can't ever be stressful taking care of her, but she has the same basic personality she has always had. I think it is probably too late for crabby lessons!
We hear so much about exceedingly nasty elders on this site. That is perfectly appropriate -- those caregivers need to vent and sometimes need suggestions. I just want to balance the record a little bit. Some elders, even with dementia, are real sweethearts.