Imagine settling into your first-class seat on a United Airlines flight, ready for a smooth journey from Houston to Seattle, only be greeted by an unexpected and unpleasant surprise. That’s exactly what happened on flight 422 when a canine passenger left a messy calling card right in the aisle of the first-class section. How bad was it? The stinky incident was so severe that the plane had to divert to Dallas-Fort Worth for an impromptu clean-up.… Passengers said a cleaning crew worked for two hours scrubbing carpets in an attempt to erase the lingering odor that plagued the cabin.