My favorite memory of shopping in Vietnam (this was 25 years ago) was the shopkeeper writing down the price on a pad and handing you the pen and pad expecting a counter offer. You usually ended up half way between the two values.

That experience changed once we started speaking enough Vietnamese, and the first quoted price also changed (went down, especially for my mother)

Or... you can go to Laos, Cambodia or Thailand. Much better experience and much nicer people

Hmm, when it comes to scams or overcharging you, Thailand is not much better than Vietnam. I remember asking 5 taxis in a row in Bangkok in some places before I could get a taxi that would agree to use the meter instead of ripping me off with foreigner prices.