What's the best way to tune my Foursquare API

I'm getting some erratic results from Foursquare's venue search API and I'm wondering if anyone has any tips on how to process my input parameters for the most "intuitive" results.

For example, suppose I am searching for a venue called "Ise Sushi", around "New York, NY", which is equivalent to (lat: 40.7143528, lon: -74.00597309999999) using Google Maps API. Plugging into the Foursquare Venue API, we get:

https://api.foursquare.com/v2/venues/search?query=ise%20sushi&ll=40.7143528%2C-74.00597309999999

This yields pretty underwhelming results: the venue I'm looking for ends up rather far down the list, at 11th place. What's interesting is that reducing the precision of the coordinates appears to produce much better results. For example, suppose we were to round the coordinates to 3 significant digits:

https://api.foursquare.com/v2/venues/search?query=ise%20sushi&ll=40.7%2C-74.0

This time, the venue I'm looking for ends up in 2nd place, even though it is actually farther from the center of the search (1072 meters, vs. 833 meters using the first query).

Another modification that appears to help improve the quality of search is substituting underscores for spaces to separate our search terms. For example, here's the original query with underscores:

https://api.foursquare.com/v2/venues/search?query=ise_sushi&ll=40.7143528%2C-74.00597309999999

This produces the most intuitive-seeming results: the venue I'm looking for appears first, and is accompanied by just one other result, "Ise Restaurant" (which is tagged as a "sushi restaurant"). For what it's worth, this actually seems to be the result set of the same search conducted on Foursquare's own website.

I'm curious what lessons I should be learning from this. Should I be reducing the precision of my coordinates? Should I be connecting my search terms with underscores, and if so, does that limit how a user can order their search terms?

Although there are ranking improvements we can make on our end to find this distant exact match, it generally also helps to specify intent=browse (although it looks like in this case, for now, it may give you worse results). By default, /venues/search uses intent=checkin, which tries really hard to find close-by matches for checking in to, at the expense of other ways a venue might match your search. Learn more at https://developer.foursquare.com/docs/venues/search