This is not to let everyone down on their short stay in Vietnam.
Like anywhere else, there are good and bad apples. The good locals give you that wonderful feeling while the unscrupulous ones just set it aside, coming from others' advise.
My best wishes goes to the driver of bus 152 from Airport to Pham Ngu Lao where I have never felt so relaxed and assured. He told me "I'll tell when you need to get off". There's practically no problem with English no matter what station in life they are in as everybody can manage to understand, and if they can't they can easily grab one translator within reach.
Secondly, it was a heartwarming gesture for the lady vendor selling those transparent sushi rolls near the Sheraton Hotel area and just north of the strip where all the local girls, ladies, and Cindy Crawford wannabies garbed in their latest and greatest national dress are having their pictorials and posing with the blooming spring flowers and a giant dragon made of thousand of ropes as backdrops. Going back, this lady was selling these transparent sushi spring rolls for three for the price of 20,000 dong ($1). She offered me special treatment, letting me sit on her stool while eating and offered me extra sauce, peanuts, and carrots and chopsticks and tissue paper (toilet paper) as well to help.
But this noon, Ben Tanh market was closed and the hawkers at the surrounding sidewalk were having a good time and very soon will be laughing all the way to the bank as they have jacked up their prices by double (pho normally selling at 20K now at 40K). While I was waiting for my order, a persistent lady came with her in-my-face style about to open two cans, asking me which one do I want - soda or beer. I asked the price and she quoted me 20K ($1). Expensive, I declined. Then her team mate was watching me eating and when I finished, she gave me the moist wipes in sachet. When I stood up to pay, this earlier pushy lady, held me back asking me to pay for the wipes. I thought it was the same extension of graciousness and hospitality I received yesterday and I fell for another true and tested modus operandi of some unscrupulous vendors.
Earlier on, I witnessed a snatching incident in the same market. Everyone seemed to be sleepy and I was one of them. I was walking and a motorcycle riding snatcher in my direction whisked by and grabbed the sack of one of a bunch of unsuspecting ladies in my opposite direction and walking on the outer curb of the sidewalk. Her shoulder bag is the shoe string type and she was in the outermost among the bunch. I only realized it when she suddenly screamed and making some tantrum gestures, aroused from her half sleep and holding and showing the strings with the sack gone. The guy just drove by casually and there were no volunteers to help.
Welcome to Vietnam, business as usual! Immature travelers exist everywhere, and the one with the shoe string strap pack learned the hard way. People need to do a little research before attempting Vietnam (this is not the Disneyland they believe it to be). The practice of charging for wet napkins is simply the way things are done here - this is not home!
As everywhere, visitors (and locals in some situations) should exercise caution. The bag snatching is very unfortunate but is well publicised as something to be wary of and to protect against. That's not to say it's excusable, of course it's not, but forewarned is forearmed.
As for overcharging, your experience highlights two things: firstly, ask the price first; secondly, expect to pay more at Tet! It's an expensive time of year for Vietnamese so of course they're going to hike up their prices and they know that its easier to get a bit of extra holiday cash out of foreigners (that goes for all year round too, just emphasised at Tet). If you ask the price first and accept that price, you can't complain. And yes, charging for wet - or even dry - napkins is common practice.