If you greet them with similar intros, especially with non-sexual topics, great. Take cues when the chatter isn't welcome and stop? Great. Things like this and you are safe. Bonus points if you apologise.
Seriously, cat-calling is a different beast entirely. nothing like walking down the street to pass a group of men who exclaim very loudly, "Well, she was ugly in front but look at that ass!"
I had a customer literally drool forget his sentences every time he saw me. He'd follow me around the store and talk to me. Other folks would step in. He left me a card - at work! - telling me he'd stop, but also exclaiming how sexy I was and how much he adored me. I had asked him to stop. He had noticed I disappeared when he came into the store. He finally did stop, but it took months of discomfort.
I had a boss that would "accidentally" brush up against my breasts or ass. Small place with no recourse, and I had to quit.
There is a lot of area between these two, and I think it should be quite obvious that they are wrong, but it happens nonetheless. There is a huge difference between a nice chat or nicely asking someone out in a way that respects them and this sort of stuff. Save for the one dude that probably thought I was a prostitute, folks in Amsterdam treated me better (I was there for a fun weekend alone, spouse stayed home) - including the dude that propositioned me after chatting in the coffee shop. He was really respectful and simply asked. I talk to random people on planes and other places willingly. Most conversation is fine so long as the other person is reasonable, and halts when I ask the conversation to stop.