It is exceptionally rude for people to let their kids roam around your house and touch your private belongings, they are shitty parents
It is like when people visit you, they expect YOU to babysit their kids whilst they smash your shit up You either babysit or your house is being wrecked. No fuck that
Yes they are curious creatures but they need to know boundaries too.
Kids need to learn to be comfortable with not being entertained all the time. It is not healthy expectation to demand entertainment or behave terribly
I once had a friend whose kids used to do this. I put my handbag on the floor in my own home, she would think nothing of sitting watching her kid rifle through it - throwing personal items all over the floor - and drag an expensive bag round the floor whilst i was in the next room making tea.
I walked back in to the room and my sanitary products and mediation were all over the floor and her child sitting under my table with my bag in one hand, and a chocolate in the other hand, and then child had a massive tantrum when i tried to remove it, and the mum said 'oh shes alright' and laughed it off. I was furious so i took my bag back and let the kid scream its head off. Her other slightly older child was in my bedroom going through my perfume cupboard and spraying my expensive perfume all over herself. Told her i was going out so sadly she would have to leave
I stopped them visiting, no way would I have them round again, they were awful parents and the kids behaviour was unbearable to be around