I would contest that – it’s never “safe” to hire someone based solely on which website they advertise on. Likewise, experience (depending on how you define “significant”) doesn’t guarantee quality, either.
You need to discuss your project with the developer beforehand. Look at examples of their past work. Talk about what your project needs, and how the developer will approach it. Outline what you want done, how much you will pay, when the work will be completed, and so forth.
I failed to mention that I got my trusted PHP developer there. That’s why I’m recommending it. The site does have a ‘test the employee first’ feature that’s why I was able to assure myself that I got a good one.
But yes, I do have to agree with your point. Whether you hire online or not, you have to be very careful with whom you hire. Some employees just look good on paper but cannot perform well. You have to be careful with that.