Editor’s note: This joint is now closed. Our marathon five-stop North Texas BBQ Tour a couple of Saturdays ago ended at OO Smokehouse in Sherman. We cruised into the lot a little before 7pm, hoping to make closing time. The OO had gotten a top 50 ranking in Texas Monthly magazine, so expectations were high among the nine surviving posse members. Despite the fact they were sold out of ribs, we were impressed. Here’s some feedback from a couple of posse members. Marshall Cooper: “This place was an icon of an authentic Texas BBQ Stand; no dining room or restrooms,…