I have written for a few of those sites. Elance, Odesk and the like -- eh. Too much competition and time just scrambling for work. They were how I broke into the business. I'm a freelance writer for a living -- have been for over a decade. I make around 50K a year. DH is a freelance artist, operating mainly through Fiverr (although his gigs now sell for much more than $5) and he makes about 20K a year. Granted, he has only been at it for a couple of years and thus far his income has only gone up each year.
Textbroker is low pay, but easy, mindless work if you can write clean copy on the first pass. Payments are reliable, but you can only excel at it if you have a vast store of knowledge, type fast, and are generally a good writer. I still do a bit of writing there for clients that prefer to use the TB system for processing their orders. These are direct orders, which are set to a higher price than those available in the general author pool. There are higher paying content mills out there, which I also use for the guaranteed paid out. These pay more in the realm of $25 to $50 for a 400-500 word piece of copy.
I also sell to magazines, do web copy for private clients, and write and sell curriculum materials via Kindle. I used to ghost write for kindle "authors," until I realized I was just making someone else rich.
As for hours worked -- I start my mornings at 5:30 am and work until noon. Mon through Fri, with the occasional weekend. This leaves me free to homeschool my kids (project based learning style), hike, do DIY, and have a full life outside of work.