It's easy to spot the tourists from the natives in Reykjavík. In fact, it's so easy, it's awkward. I live in downtown Reykjavík, where at least half the population is tourists, so when I'm out, I like playing "spot the tourist." There are a number of habits and hints that makes the common tourist easy to find, and I've mastered this game.
First of all, tourists like to wear matching winterwear. No matter if they are alone, in a couple, or in a group, most people traveling to Iceland think it's a smart idea to buy brightly colored, sporty winter clothing and wear it at all times. Whenver I see a couple walking around in 10°C weather in their thick neon North Face jackets and bobble beanies—in awe of the T-shirt wearing Icelanders—I know they are most definitely tourists.
Spot the Tourist is easy when it's raining: they all hide under their umbrellas. In that case, I can't miss them, as they soon realize why the Icelanders don't have umberellas. The wind will either blow the umberella away or simply blow the rain upwards, so you get all wet anyway. Spotted: a wet tourist who wasted his money on a useless object.
As the temperature falls, some tourists (with the exception of those from northerly areas) can be spotted by their Bambi-looking way of walking on ice. Oh, what a joy it is to sit around and watch people slip and fall on little frozen puddles or putting their arms out in order to keep their balance. Some seem to quickly learn to walk like penguins on the ice, keeping their thighs close together and only moving their legs beneath the knees. It works—but I can't say it's elegant.
On a night out, you'll spot the tourist (especially the male ones) as soon as they start talking. Not so much because of the language but because they want to know your name, what you're interested in, tell you you're beautiful, so on and so forth. If you want to hide your identity as a tourist, DON'T try to chat and don't choose a specific girl/guy to "get to know"...just dance around, have some fun, and see what happens.
Furthermore, on a night out, a person who offers to buy a round of drinks for a bunch of people is a tourist. To be specific: a tourist who hasn't bought a drink in the country yet. Drinks at bars are ridiculously expensive and nobody is going to pay that poor tourist back.
It might be an interesting experiment to play Spot the Tourist in Reykjavík, following the rules above, and then turn it around and make it into a game of Spot the Icelander. If you do so, BLOG about it and send me the link!