@华金，

Exactly! I've had the same experience. It was AWFUL! The first couple times I was in the supermarket, I would politely say:知道了，我去了解下. 麻烦您小点声. But you know them, they would never 小声. So now whenever I'm there I say"不好意思，我不太感兴趣". It's a bit rude, but I really can't handle that - my ears actually hurt.