I would guess that most, if not all of the loincloths worn by the Tarzan actors were briefs of cloth or leather with leather flaps attached, but I would argue if they should be considered "fake". For me, a loincloth is more about style rather than make. For example, I've seen swim thongs with the flaps attached to look like a loincloth. I, myself would still consider this a loincloth based on it's appearance when worn. Is it a "real" loincloth, no, but it's still a "loincloth" in my opinion. The thing I have a problem with is when an actor clearly is wearing Fruit of the Loom type briefs with a loincloth. It ruins the appearance of the loincloth, kinda like socks with sandals.
I would be interested in hearing from others also on this subject.
I'd consider them fakes. Seems that I'm more puristic, or even fundamentalist, than you :)
But I'm not into violence to spread my belief in the sacred loincloth ;)
Your view is completely understood. For my own attire I prefer an "authentic" loincloth also, but also have worn the "fake" ones on occasion.
For me a real loincloth is a long strip of material passing through the legs and held up by a cord or string tied around the waist. For example Johnny Weissmuller wore a real loincloth, but it look like Gordon Scott wore flaps over briefs or speedo.
Thumbs up to Bob T, but there are the self-holding, tied ones like a bahag or a rokushaku fundoshi, but as Tarzan fashion, they're out of question, of course :)