Here’s what consumers have asked with answers from Upwork staff and previous consumers.
I haven't heard before that no one hasn't been paid before in Upwork after successful submission of work.
I have been working on UpWork, formerly oDesk for over a year now. Just like everywhere else, there is always going to be some (clients and freelancers alike) who give a bad name for everyone else. That is a true shame. Those freelancers who take their jobs seriously are still out there. The best advice that I can give anyone looking to 'hire' on UpWork, or anyone looking to work on there is to always check those who you plan to work with out. Reviews are in place for a reason. That doesn't mean that someone new to the platform won't do a good job. Everyone has to start somewhere. However, check them out as best as possible. There are plenty of legit freelancers looking for work. There are also plenty of legit clients seeking freelancers. Like everything else, if it sounds too good to be true, it probably is. If something seems off about the situation, go with your gut feeling; it's usually right.