Well I can't say that ALL locals know about it, nor am I going to try to say that this is a tactic that is used purely towards foreigners. I don't want to sound xenophobic because I am exactly the opposite of that. However, I dont' think it is any real secret that there are normally two sets of rules in any given country, one for the locals, and one for the visitors. I don't claim any moral high-ground here because this sort of two-tiered system exists in my own home country as well and perhaps to the tune of a lot more money than I was ripped off for.
My story begins in Malaysia, because that is the place that I believe it first happened to me that I am aware of. It's just a pub with snacks sort of establishment and it seemed innocent enough from all that was going on.
I don't remember exactly where we were but this image for whatever reason brought back a memory of what happened all those years ago. The place was dark intentionally, had a bunch of tables and people mostly go in there and sit with people they already know. It didn't appear to be a club where you go and meet people, you go there with people that you brought with you. I had a crew of backpackers with me and we all wanted to go to a pub for some beers. Malaysia is considerably more expensive than most other countries in South East Asia for alcohol and this has a lot to do with the Muslim government. So when you find a "deal" on happy hour jugs / pitchers of beer, you go for it if you want it.
We sat down, things were friendly, the staff spoke English and we ordered several jugs of I think it was either Tiger or Carlsberg - whatever was on special. We drank our beers and all of a sudden the staff started coming over with items that the didn't ask us if we wanted, they just put them down on our table. These items were cold towels with a fragrance like you would get on a flight as well as bowls of peanuts.
We thought this was a nice touch and thanked them for this and the staff smiled and walked away. We didn't devour the peanuts and didn't ask for any of this stuff. In most countries when a group of people are drinking little salted snacks like this are handed out to encourage more drinking because of the salt. That was not the case here and we wouldn't find out about it until we were handed the bill.
The place was basically empty and we must have had 10 pitchers / jugs of beer between us. So when we asked for the bill we were stunned to find out that we had been charged a rather extortionate amount of money for the pittance of peanuts that were placed in front of us without us asking for them. The towels were also charged for. The price of these two things added around 40% to our bill and because all of us were backpackers on a budget, we were not pleased.
I think that staff get this a lot from foreigners because before we even got nasty (we never did) one of the staff already had a prepared statement about either we pay, or they call the police. Not being interested in getting police that are obviously going to be on their side involved, we relented and paid. This was before the days of putting bad reviews online about a place so that wasn't even an option either. It is for this reason that I am very glad that online reviews exist now because places that prey on foreigners will not be able to easily get away with this these days.
Now let me be very clear here
This may, as far as I know, be something that happens to everyone including locals, in pubs. However, there is no denying that the tactic that they used by placing things in front of us that we didn't order without telling us that we would have to pay for them was quite devious and I think, an intentional way of nickel and diming customers. Perhaps this was why this place was totally empty during happy hour.
It left a sour taste in my mouth for the rest of the time I was in Malaysia and when I got to other pubs in the future whenever I was offered anything that I didn't order, I would be somewhat aggressive about telling them to take it away. There was one time that a staff member told me that I was required to buy the peanuts in order to drink there. When I asked to see the price of the peanuts on the menu, they weren't on the menu. I paid the exact price of my beer, chugged it, and left. I seriously doubt they called the police but I was out of there before the coppers would have arrived anyway.
So just be warned of "gifts" when you are in pubs overseas. If you are concerned about it ask them "how much is this?" and if they say anything other than free, tell them that you do not want it and to take it away. Inform them at that point that you will not pay for it. If they insist that you have to, get out of there.
This may be just part of the culture but to me this seems like a way of cheating someone out of a couple of dollars. I know it is a small amount of money but it just makes me feel like I can't trust establishments and I don't like feeling that way when traveling. I want to enjoy myself and not be on my guard at all times.