Dear Massi, My mother in law's habits are disgusting. She scratches her back with the forks.

She cleans her toe nail with her fingertips and then smells them. 

She uses her dupatta to wipe her sweaty armpits and chest, but later she'll use the same dupatta to clean my baby's face after she eats something.

When she brushes her hair, she rolls up the hair that has fallen out and puts in a container. It has years worth of hair. 

My daughter found it and opened it up. I had to hoover it up as it made such a mess. My mother-in-law proper freaked out when I hoovered it. She even made me open up the hoover bag to try and get some of it back.

I find it difficult taking my kids over to visit as I am trying to teach them manners, and then my mother-in-law behaves in her disgusting way.

Massi Says, You appear to have taken a very harsh stance towards your mother-in-law.
I must point out that you are a guest visiting her home.

It is unfair for you to be so critical about her behaviour. No one person is flawless.
You have gone into detail about your mother-in-law's habits that she exhibits when she is in her own home.

As much as you disapprove of your mother-in-law's antics, understand that she is not doing these things to antagonise you.

If someone pointed out such things about your own parents, or about yourself, you would certainly feel hurt by the scathing words.

Try and take a softer and less judgmental approach towards your mother-in-law.