Making money at stock photography web sites

What do you guys think of these stock photography sites?

http://submit.shutterstock.com/?ref=59350

....and...

http://www.bigstockphoto.com/?refid=wdaph9OGqi

I guy I work with says he's making tons of money just for uploading
photos he already has in his portfolio. I don't have any "stock
photography" types of photos in my portfolio, but I was thinking about
getting into it. Before I start wasting a lot of time on something
that's not going to pay off, I thought I'd check with the group to see
if people are really making as much money as they say. Sounds too
easy.

Thanks,
John