On topic though…
We turned up at housesit and found out the owners had forgotten to tell us that there was also Cows, sheep and Guinea fowl to feed. We had only applied for the sit because there was a pig, which we thought was a pet pig as it was the only animal other than dogs that were listed. Turns out it was more of a farm and as Suze is a vegetarian it was a bit uncomfortable when they told us about the piglets they used to have and were now in the freezer… 
We now have a rather extensive question sheet which we fill in for each sit, with everything we need to know. We fill it in using a mixture of what information we get from the listing, phone call/messages and anything else we ask when we arrive at the sit.
Key things we like to know:
Daily routine of pets - how long walks, how much to feed
Good off lead
Any issues with other dogs
Any medication
Arrival/departure time
Important point - we would much rather know upfront if the pets have any issues. We can normally work around anything. But we have been deceived by owners; not telling us that they are aggressive towards other dogs etc.