"Red marks" refers to any visible signs or symbols in red color that are used to show mistakes, errors, or negative feedback in a test, document, or any other assessment. Full definition
No matter what style you choose, your bra should not leave red marks on your skin. (mommyedition.com)
It also leaves red marks on legs worse than my other brands unfortunately. (sweetbottomsbaby.com)
If you are trying to grow into a better essay writer, you should get used to getting back your papers with red marks all over them. (top-writers-reviews.com)