Eames fibreglass shell chairs  

Usually refers to a problem with the oldest armshells.
The glue (I think) on the shockmounts seeps through the thin wall of these early fiberglass shells, creating dark spots on the seating surface.
I've never seen this problem on a sideshell.... yet.

I'm not sure but isn't that one of the features
found on the Electric chairs used to execute prisoners?

A shock bleed is a type of...
A shock bleed is a type of screw. So a shock mount bleed uses a shock bleed screw.
Hope that helps.
Mike

Such expertise!
You sure know your stuff when it comes to Eames!
This obviously reflects on the quality of your company's products!

It is common...
On lighter colored early shells (e.g. Parchment, Lemon Yellow), due to the translucent nature of the plastic. In my opinion, I don't think it necessarily detracts from the value of the shell. I would consider other factors relating to condition as more important.

It was
It was considered by Charles to be evidence of the "honest character of the material" of the first chairs. Of course, later on they thickened the fiberglass and the shockmount bleed typically didn't occur. However, I have occasionally seen it on later models of the chairs. Doesnt detract from monetay value, although aesthetically some people might object to it.

"A shock mount bleed uses a shock bleed screw."
That quote is so good I might actually frame it and hang it on my living room wall.

I'll go with the majority...
I'll go with the majority answers on this one, and leave the whole shockbleed screw thing to the regulars!
Thanks to everyone for the quick response.