If you have multiple writers on your blog, how can you check that they are submitting original content and not a spin article. I use the free copyscape version but is there anything better.
Personally i wouldn't allow anyone near my blog as a writer if i had any doubt that they would be submitting original content. Better to trust your writers first than a site or software.
If you are hiring reputable writers and paying them enough for their time/talent, you shouldn't have to worry about plagiarized content. If you are hiring writers that do not have a verifiable track record, testimonials or recommendations and you are paying them very little for a large number of articles, then you can almost guarantee the work you receive from them will not be 100% original.
I have hired a few writers over the last couple of months. One of them came with very good reviews and her price was high, but I accepted it. She started by writing good articles but I noticed the quality wasn't there near the end and I almost got the feeling that she just didn't like the topic but had to finish the agreement. That's why I got a bit worried that I don't want to be in this situation again.
I usually using Google, ie; http://www.google.com/#hl=en&q=Goin...ls+of+the+person&aq=f&oq=&aqi=&fp=-Pw1cEIpNGU
Well, interesting question but I think you are already using one of the best tools available. Outside of outright firing writer who decides to use plagiarized content not much you can do. With outsourcing you have to put some trust into people you hire, just do a diligent control as you already do and you'll be fine
Normally I would suggest that for the content as well but without the quotes, you get "pretty close to it" results as well and that takes into account spun articles. Have to admit that I agree with pipes up there though: I would have to trust them before I let them near my blog.