I've been using foam for "non-traditional" dry flies for years now. They have specific uses most of the time for either very fast or very dirty water. The two main flies I do with foam are White Flies for the Susquehanna and Elk Wing Caddis for small mountain streams with fast water. In both cases the added flotation helps.

I buy cylindrical foam and cut it to the length of the body or hook shank. Then using a razor blade I slit the foam length-ways, halfway through the cylinder diameter. I then slip the foam cylinder over the hook shank with the slit opening on the bottom of the hook and rib with tying thread; voila, instant foam body. From there I build the rest of the fly the normal way. I also do extended bodies the same way.

I get my cylindrical foam from Bill Skilton:
[url=http://www.billskilton.com:e9d4a]http://www.billskilton.com[/url:e9d4a]

If 50% fake is anyone's criteria for a lure than color me a lure fisherman. My White Fly spinners are made with a Fibbette tail, foam body, and a poly wings. The dun version only has natural hackle. Beetles, bees and inchworms are 100% fake too.

In Pennsylvania the banned flies on FFO waters are molded facsimiles of bugs or baitfish. Normally constructed flies "wound about the hook" are legal and that definition suits me fine.