I have had a few of these the last year or two. Never been paid. More than half of them are a waste of time. I have refused quite a few of them.

The last "shouldn't take you more than two hours" exercise that I was given involved jumping through hoops to get set up on Instagrams API, only to discover that I was in a sandboxed mode, and needed my account approved before i could get anything more than metadata out). I didn't even get started coding, so I am not sure what exactly the test was meant to achieve.