https://foursquare.com/privacy/

Anyone who uses foursquare may not be aware that their check in information is published online for anyone to access including links to friend’s accounts and their information.  (Your total check in history)

Basically, if you check into your home the most often anyone who searches your account online can find out where you live (foursquare displays your top three visited places on the main page)  and when you’re not home, if you’re checked in else ware. 

My suggestion.. If you still want to use foursquare….

Check in only at public places. Not residences. (even friend’s houses)

No need to delete your account because you can go back and manually delete check ins online.  just click where it says check in history.

Hope this is helpful. Forward this link to anyone you know who uses the foursquare ap. They will certainly thank you!