yes microworkers is legit, they pay workers, and employers get jobs done. The only bad thing is that people do not know how to use the site. I used microworkers for about a year as an employer and made many thousands of dollars... hence my name.. I want to let you know about another website that is similar to microworkers, and it is called outsource army. outsource army even pays users better than microworkers. There is a job on outsourcearmy that pays 75 cents for all countries, on microworkers, the same job only pays 10 cents. So if you are looking for work to be done then OutsourceArmy is definitely better for you than microworkers.
If you are an employer trying to run CPA offers on the "jobs" sites, then you just have to be careful of the terms for each particular advertiser. I recommend making completely separate accounts with your advertisers and specifying that you pay people cash money to do their offers, and try the services. I have found much success with this bit of honesty and transparency with even the strictest of advertisers who say strictly no incentives.. Then they let me run their offers on these job type of sites.
just go check out the OutsourceArmy