Just a thought....
How long will it take before a microstock pic attracts a big fat lawsuit because the model/location are not properly released...?
This is not just an issue for Microstock. e.g. Alamy does not require proof of model / property releases for images. iStockPhoto is actually one of the better ones in this regard. They will not accept any picture containing a recognisable face without simultaneously uploading a copy of a signed model release. Other sites are much less rigorous though.