Miss Manners says that the host is to clean up after dinner guest -So I would think this falls in that category. But for me it comes down to showing respect to your MIL. Pick your battles wisely

Apparently, your MIL raised the man you love. For this you must overlook the little things like this. It's no big deal. Clean the table after she leaves and don't say a word.

I think it goes back to how you were raised. As kids we always had to pick up after ourselves and had to dishes after every meal. So now, regardless at home or at friends, I always take my glass, dishes, whatever, to the sink and volunteer to clean dishes and the kitchen. I think it is only courteous, but maybe your mom-in-law was raised with guest being treated like guest. I agree with the others that say don't sweat the small stuff, you'll be less stressed!

This is starting to sound like a DIL-MIL war front ..........
...........and no matter what MIL does, it will be considered wrong.

As I suggested before, Don't Sweat the Small Stuff!

IF this is all bothering you SO much,
speak with your husband about what is troubling you.
And work it out with him.

If this is the worst that is happening in your life, you have a great life. Enjoy the quirks and foibles...life is very short.

I usually pick up glasses from everyone in my family so picking up a glass from her would seem normal to me.

Do you like your MIL?

How often do you see her?

How old are each of you?

There probably is "more to the story" - but from what you've said - my reaction is "oh, good grief!!"

What do you WANT her to do?

I really think it depends on family dynamics, not etiquette rules.

If I am a guest at a family home I am a pitch in sort of person. I always will help clear tables, wash pots etc. If I know the hostess is particular in how her dishwasher is loaded, I rinse and stack. If I know how they load their dishwasher I start to load after rinsing.

My kids have been taught since they were little to clear their plates and others, when visiting family and close family friends.

But having said all that, when my mum comes over and has a coffee, the cup is left where she was sitting. But if she was over for dinner, she would be helping clear up.

I cannot imagine anyone in my family bring fast food to my house to eat, let alone leaving the wrappers out. Unless they were bring it for everyone, but still garbage is garbage, not dishes and should be put in the garbage can by the person who creates it.

I do not have a great relationship with my MIL, but I really would not care if she left out a few dishes.

I do not think that would bother me.

etiquette "rules" are not all black and white. A lot of them seem black and white because they are accepted by most people as the tried and true way to handle a particular situation. They are common sense guidance for handling people interactions in large or small situations. The main purpose is to make interactions kinder for each other.

For your specific example it really is a matter of "whatever works for all". She may feel(as well as your mother- ask her) as a guest in your house she should not assume where you want the glass. (When I was little we were taught to put things on the counter next to the sink. This way you didn't have to remove everything from the sink to wash them). When you go to her house, as a younger, more agile person it might be nice to help put dishes in/near the sink per her wishes. So - do whatever works best.