One of Gary LaFontaine's flies, the Rollover Scud, was designed to 'fall' hook side up.
When the angler started the retrieve, the fly would flip over.
Gary was a big believer in 'triggers'. Something that would cause a fish to attack a fly.
A fly like this would be best for for sight fishing, as the fly needs to flip at the right moment to trigger the attack of an already interested fish
The rollover scud is tied with a piece of lead lashed to the top of the hook shank as opposed to the bottom like many other weighted flies.
There's no reason other flies couldn't be tied this way.
But like I said, this is a fly for a special application
The simpler the outfit, the more skill it takes to manage it, and the more pleasure one gets in his achievements.
--- Horace Kephart