Where do you set the bar determining who is honest or trustworthy?

Of this question people tried to give me the impression that everyone is equal in being honest, or at the least, should be viewed that way. No matter who you are, there are cues and logic that leads you to whom you would trust with what, and to what degree. An old woman on a walker, at the mall wanting to use your smart phone to call her daughter somewhere else in the mall, that she is ready to go, so the daughter can meet her in front of so-and-so shop will have an easier time. She will be seen by most, more trusting than some young guy with saggy jeans, piercings, and prison-looking tattoos, at 10pm at an ATM with no one around.

You let strangers in your house, but which stranger and when you let them in is not all around equal. You need to repair the floor because the water heater burst, and the insurance company sends over someone to estimate the damage to see what it would take to repair it, you do not know if they will rob you once they got there. If you feel they wouldn’t, and that is why you let them in, why not have that same trust for rough looking young lady smacking gum who want to use your restroom at 9pm? Or the man that looked like he just slept under a bush the last 3 days?

Why do you give your keys to the valet, but you won’t give it to some stranger who says he will drive it to the far side of the parking lot where his youth group is detailing cars?

Everyone sets the bar for trustworthiness at some level. Where and how do you set yours, what is your criteria?