specific qualities hmm, usually i'd try to see if they have similar interests (can literally be as small as art or something. i'm not the best at interacting first when it comes to someone i don't recognise so having a interest i could mention would be a good way for me to get some information about them), and if they don't give off any bad vibes right away then yeah i wouldn't mind being their friend after getting to know them for a bit
and if they do give off bad vibes, i'd just try to limit my interaction with them and see how they are with other people first, if they seem okay then i'd try befriending them, if not then i won't befriend them. i try to trust my gut and logic a lot when it comes to this
basically, no bad vibes sure why not. yes bad vibes i'll see first then yes or no