My grandfather is 92 and has vascular dementia. He's been incontinent for over a year but mostly he would poop in the toilet on his own. In the last 3-4 months though, he has started pooping his pants almost every time he goes. He only goes once he smells it and I can't tell if he's just being lazy, or is completely unaware that he's soiled himself. Because he has stated in plain English that he won't get up to change his diaper if its just urine. Lol I love my grandpa.
IMO the best you can hope for is to catch it some of the time, so make it routine to detour to the toilet every time he is up on his feet.
If you are his primary caregiver, does he go into the toilet when you ask him to?
If you take his arm and say “Let’s go in and use the toilet” will he cooperate, go with you and sit on the toilet?
If he will, you can try him on a schedule, toileting every 2 hours, more or less often if you can observe a pattern to his needs and habits with the toilet?
Once the diagnosis has been established, I’m not personally comfortable accusing someone of being “lazy”, especially if they’re 92 (or above!)