"You should keep in mind that, if you are a frequent visitor to restaurants, you may experience various shortcomings in the food served." or "Frequent visitors to restaurants should keep in mind that they may experience various shortcomings in the food served." I changed the initial passive clause to active, to match the later clause with "you" as the subject. "there" at the end is not necessary. Two clauses in the same sentence with "should" seemed excessive. "drawback" is more "disadvantage" whereas here, you want to say that the food will sometimes be sub-standard.