I can't say as I am much better. Whenever I do any plumb work I inform the customer that I get salvage rights on anything I rip out. Most of them are fine with it. Most contractors do that, but some people pitch a fit over it. Nine out of ten times it's really just old, old copper or nickel pipes and fixtures that need to be recycled.
What happens when the customer does want to keep their old pipes? After all they are theirs and not the plumbers pipes.