The room, location, hotel staff all 'OK'. It seems that hotels in this area have started to do the dirty laundry scheme. The find some towel, sheet, floor matt, that you've used and insist it is too dirty to be cleaned. In this case it was a bed sheet. They wanted me to pay to replace it. Luckily my Thai girlfriend was wise to the scheme and made argument, taken the sheet across the street paid the laundry shop 20Baht to clean the sheet. No problems. Other wise I would have paid 2,000 baht to replace it. This has happened at some other hotels that I have stayed at as well (in this area only). It seems to be an old and familar scheme to locals but not tourist.
Hence, before you leave, make sure all cloth items are free of noticeable dirt, or travel with a local person.