I've found that some parents really don't know what to expect or what questions to ask during an interview. I make sure I'm taking the lead throughout. I go through my policies, schedule, payment, etc., asking if they have questions a few times during, but then when I'm done (and I feel like they've asked all of their questions), I'll hand the paperwork to them, say something like "It's been really great meeting you and your LO. Here's my contract and policies for you to take a look at at home. Please email if you have any more questions." with a nice, big smile.
Usually they get the hint, but if they didn't, I would stand up, start tidying, mention that I need to get my kids off to bed, etc. Or, get their coats for them, walk to the door, etc. Or even say "I'd better stop taking up your time, I need to get my own kids in bed. We'll be in touch!"
About the dumping, I totally expect that my playroom will be a mess after an interview. Most only children aren't necessarily taught how to play with only one toy at a time, and most first-time parents don't know the unspoken expectation that they should tidy up after their child.
Just my thoughts, maybe someone else will have a more direct approach to ending an interview
