My wife and I are from the States and booked a self guided trip all around Ireland this past July through a travel agency. We stayed in 13 different places that the travel company booked in advance and gave us vouchers for each night's stay. Ash Cottage was our first B&B after a night's stay in a Dublin hotel. We arrived around 9pm after a day of sight seeing but no one was there. We waited around for 45 minutes before the owners showed up. They were surprised to see us and told us there were no rooms available (even though we had a confirmation in hand). After some discussion, they said that we should have called ahead to confirm because after 6pm they assumed we were not coming and had sold our room to other people. So, even though we had a room booked and paid for, they were being greedy and sold our room (in essence getting double money).
The only reason I am giving them a rating of 2 is because they called around to find us another room in another B&B. They also did give us the money for the new arrangements. Had they not done that, we would have been pretty much out of luck. It was 10pm by then and we didn't have any means of finding other accommodations.
The rest of our trip we made sure to call ahead to make sure our rooms were secure. Once was from a payphone on the Aran islands which cost about $25. Most other establishments didn't seem to think that was necessary and were somewhat confused by the phone call. We're still not sure why the folks at Ash Cottage needed the advanced notice.
