My quick take on all this subject might not be correct, but I think it is close.
Let's say I pluck a photo off of Southern Charms of some great looking MILF. This has happened here many times.
What I think is OK is asking if this woman was catfighting another woman, who would win? That is a professional picture released for promotion, you are promoting her by attaching he picture. Doing that with a photo off of flickr with a woman who obviously does not model professionally I think is a little harder to peg, but this woman did place her photo out in a public venue, and since no one had to hack a password to get the image, I think it would be OK to use. If you take a picture of a woman walking in a public area, and do the "would she be a good catfighter" stuff, I still think you are OK unless you can see up her dress, down her shirt or if she is under 18.
Now if you say the pictured woman is yourself, I cannot see how that is OK. It better be you in the photo.
As a producer, my photos are here, on blogs, on other pages, and I have no problem with that. That is promotion. Now if it was pictures of my wife, I would not be crazy about that because she is not part of my website.