Right now it isn't very useful as there is only one pertinent criterion (swimming pool) (therefore this isn't very selective) and the database isn't shock-full of properties (therefore there isn't much 'noise' in a query result).
However I bet that, with time, other boolean criteria will appear while the DB will grow, leading to more and more need for selectivity (weeding out 'noise').
However I bet that, with time, other boolean criteria will appear while the DB will grow, leading to more and more need for selectivity (weeding out 'noise').