I think I posted about this a few times in the past, but I'm adding other links now, too. I recently came across a new blog that uses photos of men and they had a disclaimer at the bottom of the blog that stated they aren't doing anything for profit and they will take down any photo that might be an infringement. However, even though their intentions are honorable and they aren't actively trying to infringe, by using photos without permission that's exactly what they are doing and it's not a chance bloggers should be willing to take. If you don't know the photo/image is fair use or in the public domain...for certain, without a doubt...the safest thing is to not post any photos on a blog that could land you in trouble.
I actually go through all my previous posts often to make sure I'm not infringing, and I have almost four thousand blog posts. I'm not blogging for profit and I'm not promoting anyone or anything here, however, that doesn't mean I can just post a photo without permission from the person who owns the copyrights. If you notice, now when I do use a photo I provide attribution and I always link back to prove I'm not infringing. I have also heard cases where even that's not completely safe anymore. In some cases photos were put up as fair use without the owner's permission and the owner took legal action against the blogger.
And they don't have to provide you with a take down notice. It's not required by law, and you can read more about that here. This is a detailed post about fair use that may sound too cautious. But sometimes you just can't be too cautious.
This post goes into more details about bloggers and photos. This states it very clearly:
I think that second line is extremely important.
Here's a blog post that actually mentions disclaimers and photos. But once again, it's very ambiguous and as far as I know the copyright laws are just as ambiguous...they are all over cyberspace. And it's not a chance I'm willing to take. But I do suggest reading this one in full, because it talks about other disclaimers, too. More important, you have to protect your own photos from infringement as well.
This posts tells you where you can find safe photos to use on your blog. There are many posts like this with a simple search. I like wiki commons and morguefile.com
Anything can happen now, and it can happen to small bloggers and the most famous people. I posted here about Sarah Palin's S PAC being sued for copyright infringement by a New Jersey newspaper. and they mean business.
The bottom line for me is don't post any photos you don't have permission to use, or that you aren't sure are fair use or public domain. And if you choose to put up a disclaimer and you think that's safe, you still might be taking a huge chance. You are basically using someone else's property without permission.
You can ask for permission. I've done that on occasion with models and actors and all have been gracious each time and granted me permission. But get it in writing first.