A VERY popular restaurant in Seattle that operated as cash only suddenly closed and filed for bankruptcy just last week. Looks like they were up to no good. This place had two locations with lines around the block every day. Even in crummy Seattle weather.
http://blog.seattlepi.com/thebigblog/2014/11/13/paseo-files-for-bankruptcy-day-after-sudden-closure/#28355101=0&7298103=0
I always think it's a little shady when places are cash only.