What do you do if you do not trust the owners at Meet and Greet?

I learned the hard way that animals need to go in the yard to potty before coming in the house. The excitement of being in a new place combined with driving in a car seem to get the bowels and bladder going. Letting them potty first seems to avoid MnG accidents. That said, even well trained dogs can have accidents in a strange place.

Ask them if their dogs are crate trained. If so, maybe they could bring their crates so you can keep them safe while you're away 9-5. If that's a no, look into buying an indoor fence that you can place on an easily cleaned floor in case of accidents and away from temptations of counters and anything else that may catch their interest.

If you really wanted to throw caution to the wind (and not use crates or playpen/fence), you could ask them to bring them over for some time during a weekend day. I'd suggest booking this as a service, and modify the rate to what you think is fair. After the dogs had a walk with you and seem calm/relaxed, go outside for a while, and see what has happened upon your return (unless you can set up some cameras -maybe using your 2 phones?- to watch real time).

I'd comment it's more about trusting the dogs and their behavior than the owners. Putting too much trust in a dog, who will be in a new environment, that can't resist temptations may be a mistake.

My advice is to trust your gut feeling. If you're uncomfortable after the meet-and-greet, don't book.

Pooping in front of you can be an extreme marking behavior called middening. The animal wants to make it very clear he's uncomfortable with you entering his space. I've only had one dog do it as I entered his playroom, but you'll see it all the time in multi-cat homes. In my case, the dog was fine once the owner was gone and he didn't feel he had to guard her. But trust your instincts. It's better to refuse a booking than get stuck in a situation with an unhappy animal.

I actually would take a different approach and do a trial run with them first before the 5 night.

On long stays I recommend to the owner that they leave their pet with me either as day care or overnight one day prior to their stay to make sure that their pets are going to do well. So far, I have not had any push back from the owners. Not only does it give you a piece of mind but also the owners.
Best of Luck!