I don't really mind if they are used to share about my blog, or a couple lines of an article with a link back to it, but I do mind when they are out right stolen and presented as the work of another. So I added a general permission clause to the bottom of the blog. It gives permission to use images in what I consider a generally acceptable way, it also leaves no excuse when someone takes something without permission (note: clause or no- it is still illegal to take another's work without permission). Why the note about sharing on social sites? Because if you check Facebook, Pinterest and etc terms of service- they actually leave that buck on the user, they take no responsibility for anything on the sites. Any image you pin or share you are stating you have the right or permission to do so, so I'm giving that permission in most circumstances.
I've also been trying to add our blog url to my images to further discourage our images getting used for other purposes without being asked. I think I am on the same page with many people, I don't mind that my images are used or shared, but if they are being used for any reason other then to share about my blog I would like to know. Which means I need to be contacted and asked (and my email address is on all pages of both my blogs). It may seem silly; as some of my images are hastily snapped and slapped on a post to illustrate something random or to show what the boys are doing before they stop. Although if it's my family then I really want to know before they are used for anything but to link to our blog.
Some images, however, I spend more time on then I probably should- like my new background. So, seeing someone take those kinds of images (which is technically stealing) and using them for their own purposes without asking is not a happy moment. An even less happy moment were the ones where people copy and pasted my articles written using my time and research and posted claiming them as their own. A few of which I had to contact site hosts to get removed. That is plagiarism and everyone is aware it's stealing.
There's lots of legit places to get free images from. There's also lots (lots lots lots) of bloggers and writers who love to trade writing posts with others. Many bloggers have trouble coming up with daily posts. Instead you can write two or three a week and then trade guest posts with writers of similar blogs to fill the rest of the days and mutually reach new readers. Win Win. And no reason to steal the writing of a different blogger.
I also wanted to share this post link, about a blogger that found out the hard way that these laws are very real, and very serious- http://www.roniloren.com/blog/2012/7/20/bloggers-beware-you-can-get-sued-for-using-pics-on-your-blog.html. So even if someone doesn't agree with the moral or ethical reasons not to use images without permission or plagiarize... everyone should be aware of the legal reasons. One of the reasons I am so careful to take the time to create and use my own images is because I do not want to deal with what this blogger had to.