I have for many years now, spent most of my days, answering online surveys. They pay usually up to £1.00 or so each, and I do them online. Next week I'm going to Russia on a Tourism visa. Can I legally continue to answer the surveys while I am there? My application is as unemployed, because predominantly I am. The surveys take up my whole days, usually, and mostly only pay every few out every few months.
This question comes up all the time. Two things
Tax wise you are not working in Russia. You are paying your taxes in the UK.
Theoretically, the FSB or whatever can spy on you to find out what you are doing online. In practice there are like 35 million tourists a year in Russia. I will let you guess whether they do.
This sort of work we digital nomads do is not well regulated and falls through the cracks. Who will know whether you are filling out a fun quiz (which, by the way, if connected to Facebook, will just expand the profile of what advertisers know about you and you'll be surprised how much personality can be learned from favorite movies but I digress) or getting paid for it.
We usually do not encourage breaking the law on this site but the definition is very blurry here.
De jure there are dozens of complex laws and regulations regarding remote employment, under which you may or may not need a special visa in order to work in a given country. Tax laws are an additional complication, where countries such as the UK can deem you as a tax resident for spending as little as 16 days on British soil.
De facto, as long as you don't mention your remote job to immigration personnel at the airport, there's a 99.99% chance no one will ever find out. There are millions of people breaking the law by being employed at on-site jobs in any given country, so digital nomads are a pretty low priority for law enforcement.