Howevere I have ntoiced this traffic tenms to be of a lower quality as it has significantly less pageviews per visit, converst at a lower precentage and has a mmuch higher bounce rate.
Unless your product os very nclosley tied wityh imagry I would not bother to much.
"A big pile of unmitigated bollox form a guy who cant do SEO." (and doesn't know how to type or use a proper browser with a spell checker)
Including images that are hosted on your server is good for Google and other search engines because it shows you have more content, if you block them from being indexed just because Google image clicks are "lower quality", you may lower your page position and thus lose important clicks.
There may be a drawback if people are posting the pictures without you checking them, Google can cut off all search results for your site if they get one DMCA notice letter. Make sure you check the pics.
So like I've said before in other threads, don't depend on just Google for all your traffic.