I have sent phones to them in that condition and never had a problem. I.e I don't keep a protector on any of my phones and they have never discounted me for scratches to the display. Their condition spec can be found here but is quite ambiguous. https://www.musicmagpie.co.uk/condition-specifications/mobile-phones/With regards to music magpie etc what are they like with light marks to screens etc? Mine has small marks visible from having no screen protector.
only visible if screen is off and tilted in the light