Andrew is right, but the only time i will ask someone to change it is when i get a complaint. I got a fast connection at school and home so it doesn't bother me. but if i get complaints then i would ask them to change.
I have heard one other person in the past week complain about sigs, and since mrmacdude named some poeple i will now ask for all those people to shorten their sigs. Disturbed already got his, so would the others please do it.
And like sab said you can turn the sigs off if you don't want to see them. but some still need to be shortened