High-quality, relevant images presented in a clear and accessible way (e.g. using alt attributes) can provide an SEO boost to websites, especially via Image Search engines.
I was wondering what the SEO implications of hosting 3rd party images would be.
I'm considering using the website thumbnails available from Thumbshots to help supplement a project to catalog the privacy and safety of millions of websites across the web. While I know these thumbnails will improve the quality of my site, I was wondering what their implications for SEO would be.
The way Thumbshots works is that they serve the images from their server. One idea I had was to serve their images via proxy through a URL on my own server, if that would be better for the SEO of my website.
I don't think WHERE images are served from has as big an impact on SEO as you seem to think. Serving the images yourself will cause your site to load slightly slower, which COULD have a negative impact on SEO.
However, good SEO takes user experience and ease of use into account, and it sounds like you're actively thinking about that already.
I've used CDNs in the past on image-heavy sites, and have seen a boost in loading times because of it. My main concern here would be legality issues.