Last summit register I saw was on Mt. Washington. A big-ass ammo can with a half-sheet of folded paper and a pen. Although it didn't particularly ruin my summit experience (the 6 Mazamas clogging the descent did more to further that end) I did find such a large can with so little in it sitting in the middle of the summit plateau obtrusively, pretty lame.
Of course signed it, gapertimmy style.
I think they are trash too but I'm not going to get my fishnets all soiled thinking about it. I got bigger things to worry about like if my shoes match my harness and how to tuck that string back in.