Some Foursquare users add irrelevant places to Foursquare. To ensure BlindSquare announcements are actually useful, BlindSquare will filter these places and only announce venues where at least five different users have checked in.
If you have found a Foursquare venue that BlindSquare does not yet announce, you can either ask your friends to check in to this place, or you can add this place to My Places to have it announced always.
Open the venue’s Place Summary Screen and find the Favorite button. When you double-tap this button, the Foursquare venue will be added to My Places.