Switzerland may be a sellers' market, but it is not unreasonable to expect the flush the toilet and run the shower to see if it has enough pressure and so on. I suggest making an appointment to 'measure up' to see if you furniture will fit and tell the owner it will couple of hours and really get the feel of the place.

I would also recommend hanging about outside at various times of day to see if kids play football under the windows, commuter traffic can be heard and that it's not on the southern approach to the airport...