Old money in the most literal sense

Often when I travel, my family will give me dribs and drabs of foreign currency from some trip they took 10-30 years ago. It's super generous and I'm always happy to "help out" and use up their old paper money and coins. They're highly organized so it's always in little ziploc bags, but the money is often kinda "vintage" which frequently lends to some funny looks and comments when I attempt to buy anything. Hey, money is money right? It's a good way to meet the locals and it sure makes for some good stories. Now, I just need to plan a trip to Brunei to spend the lone $1 bill I found accidentally stashed in my Singapore ziploc. It's worth about 80 cents US.

Dunkin Donuts - Davis Square
DDLady: That'll be $2 for the medium coffee.
plasticann: Here's a $20.
DD Lady: [looks at the bill] This is really old money, but it looks brand new.
plasticann: [slightly embarrassed] It's from my grandma.
DD Lady: [smiles] It's always the grandmas. Ha ha!

Clothing Store - Vancouver
plasticann: I have some "older" money, will you accept it?
Cashier: Let me take a look.
plasticann: [hands over the bill] I was going to exchange it for a new one at the bank, but if you'll take it, it'll save me a trip.
Cashier: Oh my goodness, I've never seen this type of money. It's REALLY old and it looks brand new. My dad collects old money, I think I might go to the ATM and get a new one to exchange it for this old one.

Food Court - Singapore
Cashier: It'll be $8.60 for the pork BBQ.
plasticann: Here's a ten.
Cashier: [examines the bill and shows it to an older guy as if to ask, "is this real money, I've never seen it before. Older guy nods in approval and she accepts my bill]

Coffeeshop - Singapore
Cashier: It'll be $6 for the flat white.
plasticann: Here's a ten.
Cashier: Oh my god, this is really old. It's like an original. [Shows the barista]
Barista: I haven't seen one in a LONG time. I've never seen one in such good condition.

7-11 - Singapore
Elderly cashier: The total is $3 for the waters.
plasticann: [hands over three $1 bills]
Elderly cashier: These are like originals. They don't even make $1 bills anymore. It's all coins.
plasticann: ummm, will you take it?
Elderly cashier: Yes of course.