My US stamps in my US passports have been stamped in some of the most disruptive way possible -- things like CBP stamps on my visa stickers/stamps -- and it's been done seemingly mostly by way of carelessness than anything else.
I haven't cared to check if some of my visa stickers/stamps have been placed over US CBP stamps in expired/cancelled passports, but I wouldn't expect to encounter that a lot in my passports. Not all alterations done to US passports by individuals in a private capacity is against US law, but alterations increase the risk of having some kind of problems using that passport. And some of this may even go for expired/cancelled passports.
The general rule I have is that the newer and more pristine the passport looks the less likely it's to give a problem in its use -- except under a very limited set of circumstances.