WARNING! Some websites object to people linking to their photos and some object to you using them at all, even if you copy and host them yourself.
Some websites will even substitute the picture you thought you linked to with a notice that you are stealing their bandwidth. Others have been known to substitute porn in place of the image you think you're linking to.
Best to host the pictures you are posting on your own website
True. I've posted thousands of pictures over the years and only had one turn up with a tsk-tsk replacement. Most sites that don't want you to use their photos will say so somewhere on the site, and of course copyrighted images are certainly off-limits. Don't want to get FR into trouble, don't ya know.