Off thread but never mind! I heard a humourous management talk a couple of years ago (no, hang on, I haven't gone insane!) in which the speaker recommended dealing with such non-conversations by forcing the conversations in strange directions.

Instead of Salesman: Can I help you?
You: No thank you, just looking

Try

Salesman: Can I help you?
You: With what?
Baffled Salesman: Pardon?
You: What do you want to help me with?
Salesman: I don't know ... I was just told to say that!

Try it - it usually does get that response!