Heidi â€” Just reinforcing Anne's message.
I take the approach that unless I have specific permission to link to an image or web page, I always link to the home page and provide the navigation or route to follow to get to the image or page.
The reason is simple. By linking directly you are usually bypassing whatever pays for the site, whether that is third party advertising, exposure to their shop window of tempting offerings, or something else. You are gaining benefit from their website without paying for it. And that is unreasonable, and could be considered theft of the website proprietor's allocation of bandwidth. And if they discover or suspect what you have done, all they have to do is change a few filenames, and your link could be pointing to a less than appropriate image â€” I will leave that to your imagination!
That's why you should always link to the eBay listing rather than the specific image in it. Oh, and if you suspect that someone is doing this to your eBay images, just revise your listing. All the eBay-hosted image URLs will change.