Hi Anna,
I know exactly what your talking about. I experienced this with my Mom and it caused quite a stir when it came to visiting family and friends. My Sister In Law was very mean to my Mom and would make snide remarks whenever Mom was riding in her car and visiting on Sunday. She could have been a little more understanding . They eventually started putting those plastis pads on the car seat and the chair that she sat on. Anyway what I found out is that the loss of smell comes at the onset of Alzheimers . it's one of the first senses that goes. Mom didn't believe us when we told her that she had an oder. I suggested that she use unscented (to prevent urinary infections) baby wipes and to use a Perry bottle with warm water and squirt it down their to rince parts she couldn't reach. Mom had 3 hernias the size of melons on her tummy and had a hard time reaching also. When she took a shower I told her to take the water pick shower head and rince down there real good. We even had a little sex joke about that. Mom was quite a sensual lady, heehee. The thing is to not make her feel bad about herself at that age because it is a delicate topic. At one point my sister and I had to give her a shower on Mothers day before we took her out to eat. But Anna you are the best person to tell her these things before someone else says something mean. it's unfortunate that when our parents get old that we have to basically become the parent or caregiver but we do it because we love them and have a genuine concern for their wellbeing. I would also check her clothing like house dresses & robes and coats. When I was walking behind Mom after she showered and was dressed I noticed her housedress had stains in the back.
good luck and Happy Thankgiving !!
J.