So I took apart a Spider-Man today and found a few things interesting. The shoulders were VERY durable! I moved them around like crazy and did things that would stress the joint in all the wrong areas including just pulling on it pretty hard...and it held up perfectly. Now this isn't to say that all of them will be like this or that yours will be this durable but the one I took apart was.
There is a body suit that covers from the biceps to the knees.
The odd bump on the shoulder/bicep area is an odd bit of a mesh foam-like material glued on. The same material is glued over the shoulder ball joint. The bicep piece and the shoulder piece are two separate pieces intentionally. My guess is that the foam was supposed to be on the back of the arm more simulating triceps but somehow got glue in the wrong position during manufacturing. Also, the same foam is glue on the inside of the thighs. Not sure why there is foam anywhere since the body is covered in with the body suit under the spidey suit.
Also, the suit itself is extremely durable. I stretched the crap out of it and although sometimes it took longer, it always went back to normal. Even on my keeper, I had it posed with the head twisted and joints bent, stretching the suit, for over a week, but once I stood it straight up, after about a day or so, it all went back. The neck looked saggy as hell right after but its perfect again.
There was no sticking on the suit either as one or two others have reported. It was in a dry place at around 65'F but it won't be any more than about 78'F in that room, even in the summer, so I'm not worried.
Hopefully this info is helpful to some people who are worried about this figure. However, just because mine is like this, it doesn't mean yours necessarily is. You should still exercise caution with these figure and should anything negative happen to yours, I take no responsibility
