Agree with you about images and urls thats what the profile should be for. As for spam, that's just wrong.
But for quotes at the bottom of sigs, as long as it's within the CoC and not too huge where's the problem.
Also surely it takes more CPU time/RAM/whatever to change every single sig on all your posts than to just change the sig for any subsequent posts.
It also looks weird if people make comments about your sig and you go and change it, the comments won't make sense.
Just my 2 penneth.
An appeaser is one who feeds a crocodile, hoping it will eat him last.
Sir Winston Churchill (1874 - 1965)