Could You Be a Bit More Specific?

I'm still looking into this whole idea about submitting writing to various publications. The problem is, I keep coming upon this one phrase "previously unpublished work." What I'm wondering is, how picky are they really going to be about that? Because pretty much everything I've ever written, I've posted here. One place actually specified that posting something on your own blog counted as it being published, which to me sounds fucking insane. I'm hoping that since the other places didn't specifically say that, that they are being a bit more realistic. I mean seriously, where else in the world would posting stuff here possibly count as being published? If it does count then I might as well go ahead and retire as a successful writer , because I've had nearly 700 pieces "published".