So often, we go through a process when scoping out a new casual friend that is utterly selfish. We rarely think of others and how they would benefit from a conversation and smile. Instead this is generally how it goes: We start out by judging.
first we judge their appearance, (clothing, hair, body type)
then we judge their personality. (smile, friendliness, social graces, and charm)
We also take into consideration their social status and what type of people gravitate toward them. No one wants a social liability on their hands!
Once the candidate has passed these preliminary tests, then we consider them worthy of our time and attention.
A better procedure would be to see each new face as an opportunity to be a blessing. To start out with an end in mind, to discover not whether they are deserving of your friendship, But why they are.