Currently there are only very simplisitic and near useless filters in the "General Filters" for Smart Search. The filters consist soley of "last modified time". This speaks to a lack of imagination for the people who rolled out Smart Search.
Smart Search has the capability to be an awesome feature. However it's usefullness is limited by the clunky user interface and that so much of it is untouchable/cannot be tailored to meet specific customer needs.
Would be a great enhancement to allow editing/tailoring of the specified General filters.in Smart Search.