The risk is that someone can get you banned if he uploads porn pics. Google doesn't like these kind of site because the webmaster cannot control all the content uploaded by users.
Just use adsense on the entry point to the site. you will be okay. there is a rish but only a slight one
Google understands that you can't control everything people upload, I think if you make it clear in that porn pics are not allowed you will be ok.
I don't think it's possible, the amount of pic are huge, I can only rely on the "report abuse" function to monitor my site
ALL image hosting sites I ever visited - incl flickr - or found during copyright infringement investigations, so far have been hosting stolen pics at least to some percentage! revenue from stolen ( thus illegal ) content in itself is illegal in MOST countries on this planet. sooner or later you get a million $ lawsuit for copyright infringement PLUS may get your site deleted if host is US or serious country based. Photo-CREATORS ( photographers ) spend so MANY thousand or ten thousands of us$ / yr for photo creation, photo equipment and photo related travel, that all photographers most likely have their OWN domain to publish their own pics. It is quiet safe to assume that those ppl publishing/sharing pics on free image hosting sites use stolen pics in many cases.
I think there is no problem at all. You just put "report abuse" on image page. Don't you think youtube, veoh... (using adsense) doesn't have copyrighted videos hosted in their server?
Copyright and lawsuit are serious questions that can't be ignored, but can I avoid being sued by writing a "disclaimer" in my site? How can flickr, Photobucket or tinypic avoid lawsuit? I don't think they can check all pics in their server, right?
Google's ads are contextual, depending on the display page which displays the picture google will probably never know it has porn, unless you have a description of the picture or something else, it will just see the <img> tags, and have no idea what is there. That's not to say it's not against the rules. It has never been a problem for me, and I've never been contacted by Google, just be proactive in dealing with abuse reports that you receive about inappropriate pictures and make sure you have proper information on all the pictures that are uploaded. Just be careful, if you really want to be safe, you can just put it on the upload page, and not pages which you do not control the content fully, or you have no full moderation ability to control where ads are shown, and with what content.