Consistent Floating Flies
Although most fly patterns are designed with balance and presentation in mind, some dry flies tend to land and drift upside down or on their side nearly as often as they land the right way.
One way to correct this phenomenon is to trim the hackle flat on the bottom of your dry fly so that it makes more of a nice flat surface on which the fly can rest as it drifts. I do this with almost all of my conventionally hackled dry flies. You shouldn't have to worry about it with parachute style patterns.
Try this simple trick the next time your bugs seem to float a little funky.