What to do about a dog guest who damages property?

I agree with Mark F..... but what you can do is when you file your taxes you can put down the cost of whatever things were destroyed by dogs you sat for as a deduction.

I think it would be okay to mention it to the owner. Either in a message if the stay is still active or when they come to pick up the dog if it's ending soon. Phrasing it like "I left Fido in the back room during dinner time so he could eat in peace, but he seems to have gotten a bit anxious and tore up the carpeting. I don't think he ingested any of it, but I wanted to let you know!"

As Mark F. said, the owner is under no obligation to pay, so I wouldn't want to make them feel like they were - plus that could result in a poor review. But as an owner I would also want to know if and how my dog acts out during a visit so I can warn future sitters.

You could ask the dog owner. But, Rover's terms of service (9.7) says sitters are responsible for any damage to their property. This makes sense to me. The dog owner can't be responsible for how the dog adjusts to you and your environment.

I don't know what the prevailing view is these days. But, years ago enthusiasts believed you shouldn't trust a dog until it had been earned. If I left a dog uncrated and it chewed cabinets or window blinds, I would feel like that was my fault for trusting the dog more than I should have. If I let a dog wander the house and it pees, that's my fault for not keeping an eye on it, and restricting freedom with a leash if I can't follow it around at that time.

I haven't gotten the impression that view is popular around here. So, take it for what it's worth.

Boarders have successfully asked owners to pay for property damage. I would feel embarrassed to ask (since I take the above view, and it would imply I was not only careless but not taking responsibility for it.).

If you leave a dog without a constant supervision and something happens, it's on you and no one will reimburse you for any damages. It's always good to ask first how the dog does alone, in a crate or if a regular crate is strong enough and you may need to buy the steel crate? No one can blame the owner or the dog that you left a guest dog unsupervised/