My glucosamine story, for what it's worth.
About 5 years ago I tore the meniscus in my left knee in a hiking accident. I saw a knee surgeon the next day, had the surgery the day after, then spent a few weeks doing physical therapy.
After the surgery, my brother's girlfriend[1] suggested I take glucosamine to help with recovery. Having a renewed appreciation for healthy knees, I started popping the pills daily.
After a couple of months, my knee was back to full range of motion. I've not had any problems with it since. This may or may not be due to the glucosamine; we'll never know. However...
I've had problems with my right elbow since I was a little kid. I think I injured it playing football in my front yard. It doesn't extend completely, it's often stiff and creaky, and usually sore in the mornings.
One day, after taking glucosamine for a few months, I noticed that my elbow problems have mostly disappeared. I still can't extend it completely, of course (that's almost certainly a mechanical issue) but the stiffness, creakiness, soreness, and occasional popping are completely gone.
I'm definitely a "glucosamine believer". Of course, your mileage may vary.
[1] She's not just "my brother's girlfriend", she's also a surgical recovery nurse with about 25 years experience, and a vocal advocate for natural and homeopathic treatments. Regarding health matters, I take her advice seriously.