In one area I used to live in the general "proper" behavior when you are approached by street vendors or beggars was essentially 3 phase.

1) Ignore unless you intend to buy or give. This means you do not reply to anything they say or even make eye contact.

2) Engage verbally or even just visually. This means you intend to buy or give. Now you will be pressured and given an aggressive sell/ask.

3) If it was a mistaken engagement or you don't reach an agreement you MUST aggressively exit. This often means yelling, possibly swearing, and in some cases even putting your hands on someone and even verbally threatening in bad situations.

I spent a significant enough amount of my childhood growing up in this type of culture. My wife was always from a small city. When we later moved I explained to her that this was a big cultural difference than she was used to and the expected way to behave in these situations.

Being from a small city she thought this was disrespectful and continually made things, putting it lightly, more difficult for us.

Eventually it actually put us in a situation that escalated to being dangerous. A seller that she responded to with small talk became very angry that she had wasted his time. He then got in her face, put a hand on her shoulder and started screaming at her.

At that point I ran over, pushed the man off of her and said, "She doesn't fucking want anything. Now get the fuck out of our faces before I have to kick your ass."

After that happened she finally took my advice.