Oh I HATE having that happen! I remember at one stage I was renting with an ex, and my mum was living with us for a while so that she could get to uni.
The landlord brought people around at short notice because he'd called my mum who said it was ok.
I was asleep in the master bedroom (which was an absolute PIGSTYE!) and my mum actually opened the door for them to have a look while I was asleep in there! I WAS FURIOUS! It's bad enough to have someone gawping through all your stuff, but to have someone see you at your most vulnerable with clothes all over the place, and you sleep naked... I can't describe how much I tore off the real estate agent when I found out. He always made appointments with me after that.
He used to always tell me while they were there about how lovely the people were, and that they were scrimping and saving every dollar to buy their first home... Buddy, I don't care. They want to take my home out from under me. You are NOT going to make me feel sympathetic and help you make a commission by talking the place up.
*sigh* Sorry, that was just such a stressful time of my life so I can really relate. And having kids involved too That's just awful.