I bought a 100mm f/2.8L IS Macro from a used forum, they didn't pack it up well at all. One layer of bubble wrap, a t-shirt, and lots of empty space. The box was super beat up at my door.
Opened it up, and when you move the lens around you can hear it rattle a little and behind the rear element you can see moving around.
I took a couple test shots -- the AF seems to work. I can't tell if the IS is working or not, I think this has a different type of IS than the lens I have.
The only other IS lens I have is the Canon EF 70-300mm f/4-5.6 IS USM and it doesn't rattle, the only way I can describe the IS is that you can "feel" it working when you're shooting. And moving it around when it's not powered on, it doesn't rattle.. but you can kinda feel that it's floating in there.
Maybe I should make a video/recording of this.
Before I PM them I just wanted to be sure this wasn't normal with the 100mm L Macro.