As Justin said there is always a market for a house if it is priced right or the terms are too good to pass up. Duplex and multifamilies are a small market in Rockland. They appeal either to investors or those people who cannot afford to carry a single family home.
Currently there are 93 multifamily homes for sale in the county. 9 multifamilies have sold within the last 3 months, which works out to 9.68%. Their average days on market is 116, the median 81. In contrast, there are 1327 single family homes currently on the market. 357 have sold during the last 3 months, or 26.90%. Their average days on market is 96, the median 64.
As you can see, while they do take a little longer to sell, the difference is not that great. If you were to examine all of the sales closely, you would notice that those that were priced well are the ones that sold.
There is always interest in homes for sale in the river towns. What turns interest into a sale is the price.