'Tis true...
...some of us out here on the left coast have flies that are heavy enough to be cast on a spinning rod. But to clarify, it would take an ultra-light spinning outfit to do it, a Penn Squidder would not work. And, though those flies feel may feel outlandishly heavy to the uninitiated, the fact is we cast them on a flyrod, using the weight of the line to make the cast, in other words we FLYCAST them. AND, I would dare venture to say that the guys that are proficient at this game can cast these flies with more precision, consistency and efficiency than most other anglers can cast a more traditional fly rig. One other point to set forth - the weight should be in proportion to the size of the fly. The anglers "in the know", their heaviest flies are also their largest flies as the goal is not to make the fly plummet like a rock, but rather to use just enough weight to make the fly REACT AGAINST THE CURRENT and thus SWIM IN A LIFELIKE MANNER.
Are lead-eyed flies more effective than standard flies? They can be, when in the right hands. Contrary to many oft presented opinions, catching more fish on a weighted flies takes knowledge and experience, just like any other aspect of flyfishing. It is not just a matter of lashing on some weight and then chucking it out with a guarantee of "instant fish on". Heck, before you can fish them, you first have to learn how to CAST them. But, believe it or not, with the right system casting weighted flies can be not just a pleasant endeavor, but also a very satisfying one. When you can deliver a lead-eyed fly to your target area with precision, consistency, and power it's a farhookin' total kick!
One last point. The use of weighted flies is for me, not absolutely about catching more fish. The whole approach allows me to fish CONFIDENTLY in places and circumstances that have proven to be very low odds with conventional flyfishing systems. And, some of the takes I experience on weighted flies are of a nature, and come from parts of the fly's swing, that are SELDOM experienced on a traditional swung-fly approach. All of this just makes my flyfishing that much more multi-faceted and thus for me, more interesting and satisfying.
Oh yeah - one of the biggest misconceptions made is to assume that someone is "dredging" just because they have lead-eyes on their flies. In many cases nothing could be further from the truth, and that's all I'm ever going to say about that!