Warning labels are sure signs that someone has done something stupid, at least once. We can safely assume that once upon a time, a pill-popper ate the dessicant that now says “DO NOT EAT.”
However, I have not read of a mountaineering death in which someone actually used an accessory carabiner (such as the one on a keychain) as climbing protection. My ski gloves came with one of those zero-kilonewton carabiners and a warning pregnant with caution, heeding the user to remove “the carbine (sic) hook from your gloves when not in use.” Obviously, by leaving the biner attached, the temptation could be too great to use it to build an anchor.
By contrast, here’s a really useful warning:
You can decide how useful this one is: