I agree. Experience has taught me that 100% of the locals (other than the ones that I already know) who approach me on the beach want $$ in one form or the other. If I'm bored, I might engage them for the fun of it, but generally, like you, I studiously ignore them. This sometimes results in "show me respect!" comments, which is irony at its best.
The other night (8:30pm) I was walking past Alfreds on my way back to my room. There was a show that night, so the barrier has been erected. There was a group of locals hanging out near the entrance. One guy who I'd never seen before, (40's, white T-shirt and pants, drunk or stoned) saw me and made a b-line for me with his hand outstretched. I couldn't avoid him due to the narrow strip of beach between the barrier and the water.
"Hey! I remember you!" he said.
"No, it's my first time here," I replied. I didn't take his hand.
"Yes, your first time here! I remember you!" He was now right up in my face. I walked around him.
"Hey! Shake my hand! Show me respect!" he said. "Are you having a good time in Jamaica?"
I ignored him and kept on walking. He reverted to patois and gave me a blast, sprinkled with the classic Jamaican invectives.
I kept walking. When I was about 20 yards past the barrier I looked back. The dude was closing in on me, still muttering. He was clearly visible in the bright light of the full moon. He seemed angry. His posture was aggressive.
I turned around and walked back towards Alfred's where a security type was standing at the entrance to the venue. I skirted around the guy. He pivoted and stopped, watching me. I went into the venue and had a beer.
Later I walked back to my room, un-accosted.
Not a big thing but I just don't want to deal with it anymore. That's why I seldom venture onto the beach at night unless I'm with my homies.