It just looks like an "idiot scratch"starting at the bottom and going up.If the bare metal where the slide stop goes in isn't damaged I wouldn't worry too much.After all it is used.If it does bother you too much,you can always get it re-finished.Just keep it oiled and watch out for rust.Happy shooting to you.Oh,and I'm not passing judgement on anyone for having an "idiot scratch",as I am certainly guilty of the same offence.
I have seen that before. It happens when the operator can't get the gun reassembled. They think rather then properly align everything then snap the release back in place, using a screw driver or other tool to help pry it back is better.
Ask the previous owner. If he's at all honest, he'll fess up.
I haven't shot it yet but I'm sure it will function fine and I can't ask the previous owner since I got it from my local gun shop but there good people one time when my spring on my shield locked up the owner didn't even hesitate and took one out of a new shield and gave it to me and then called smith and Wesson for a replacement. I'm going there today to show them.