My opinion would be, if its checked in under their name, and would only be exposed to developers (via source code or only within a debugging env), then leave it in. Otherwise, clean it up.
I thought I should leave it, if I don’t edit the file. Otherwise I clean it up. Thanks!
A friend told me a story from the late 80’s when computers was all text based, joking and rewriting each others debug with comments like: “you stupid etc etc”… one day the client called in tears. -“the computer told me I was stupid”…so they had to quit joking with each other.