If you trust your friend's recommendation, I don't see that there is much more you can do. The letting agencies usually arrange the cleaning staff. This is why agency letting is expensive and holiday cottages are expensive.
The alternative would be keeping a close eye on it yourself. Find a local person to be your own agent.
We've rented the same cottage on a Scottish island, a few times, from a family who live in the South of England. They themselves visit twice a year and rely on a local woman to take payments on-line and clean between lets. She looks after a few cottages - and the doctor's surgery. We had to stay over our time while we waited for the ferry and she came in and changed the beds and checked everything, in record time.
But I have heard stories of holiday lets being left in a mess so it is a chancy business.