It seemed that as the 60s faded out and the 70s came along to replace an ere there was a few characters that failed to notice that the decade had changed. They were referred to as "old hippies" and they hung on tight to what they felt looked good and many of them are still dressed that way today.
It was definitely not an "off the shelf" look, because just about every customised feature that was worn during the Hippie or "flower child" era had to be created by hand. So much of what they did during that time was done on a pair of old faded "Levi" jeans. This is because, what many people don't realize is that during that time "Levi Strous" was, for the most part, the only show in town.
Sure, there were a few other brands of jeans such as Wranglers that a true hippie would not be caught dead in, due to the fact that Wranglers were the favorite garb of "red necks", who happened to be the arch enemy of the hippie. Then there were other "off brands" of jeans that were sold in places like K-Mart and J.C. Penny stores that just wouldn't "cut it" in the eyes of the true discriminating hippie.
So, it was Levis and not just any Levis, because they had to be faded somewhat. When the straight legged look went to bell bottoms in the middle of the hippie era, rather then throw out perfectly good faded Levis, many hippies adapted. What they would do is cut out a big "V" in the bottom of the leg and then stitch in some fabric of a contrasting color and design. This effectively turned what was once straight legged Levis into bell bottoms, only with a personalized unique look.