Re: garbage prevents copy from *grep* buffer

[Richard Stallman]

    Since no one likes invisible grep markers, they should be deleted
    from the grep buffer even at the cost of losing the ability to restore
    their highlighting after saving and reloading the grep buffer, or even
    after modifying the lines with grep matches.

I agree.  Would you like to do this?

By the way, if you want to "restore their highlighting...after
modifying the lines", the undo command should do it.